Dell Venue 8 7840 not booting - General Questions and Answers

Hey guys, I'm stuck and need assistance. I've had my dell venue 8 7840 for 5/6 years now and never really had any issues until recently.
When I switch my device on it goes straight into Recovery mode. When I press the power button as instructed by the device it then displays an android bot laying on the ground with a red exclamation mark with "no command" written underneath it (by the way the warning message on the recovery screen says:"Your device is unable to start because the boot image has failed to verify. You may attempt to recover the device.") After some minutes it loops/resets back to the recovery mode screen prompting me to do the same thing again (press power button).
I've gone into the system bios? by pressing and holding the volume up key and power button at the same time and I've wiped the cache partition and data/factory reset options many times but it still keeps showing me the recovery screen looping. All I want is to somehow restore my device. I know my data is gone as I've been resetting to factory which is fine. I just want it working again but all I can see via searches on XDA are guides on how to root the device which I can't do as the device isn't even booting up. Someone please help. I'm a complete novice at everything including terminology but I'm guessing my device's boot sequence has been corrupted so it just keeps looping and I'll need to somehow copy a working boot sequence to replace the damaged one on my device?

What happens when you in Recovery Menu apply "reboot system now"?

It goes back to the screen with the recovery message after trying to reboot

Related

[Q] Help with Phone Stuck Booting

I'm usually pretty good at following instructions but I have a problem. I am rooted with TWRP, stock kernel. I successfully applied the 4.4.1 update and used the phone for awhile no probs. Tried re-applying the 4 way reboot menu mod that I'd used successfully on 4.4.0. TWRP says flash was successful. I rebooted and am stuck at the spinning google colored circles. I cant get into recovery mode by holding the volume up/down and power buttons. The phone vibrates briefly when I hold all three but the logo keeps spinning. Pressing power button only does the same. Tried connecting to PC but mac says can't read device and to reboot it. ?help?
Update - Got her to reboot with volume down/pwer, into TWRP, and restored from backup, Back up and running...

[Q] 9.18.94.xt926 Stuck in Factor Rest

Hey all,
Earlier today I tried to update from stock 9.18.94.xt926 to KitKat. Unfortunately after the system shutdown and the package tried to install it failed and rebooted to advice me of so. I read online that I should attempt a factory reset before upgrading.
So, I went to settings -> security -> factory reset.
The phone shut off and entered reset mode with the Green Android and a Blue Matrix swirling on its belly.
Since then, the phone has been stuck on this same screen. Additionally, on this page, if I press the volume up/down butts on twice a yellow text appears showing...
'
ge 1/1
Formatting /data...
'
Turning the phone on and off with power + volume down results in the same screen.
The only way I can get the phone to boot is by pressing power + up, then choosing something besides factory reset on the recovery page.
However, when the phone boots its as if it is a brand new device. Additionally, if I am to power down the device, it reboots into the familiar Green Android and Blue matrix page.
Is there any way to fix this issue?
Thanks,
-Tsoju
use this http://forum.xda-developers.com/showthread.php?t=2474393

Unusual bootloop - can't access recovery OR fastboot but loops on "optimzing apps"

Unusual bootloop - can't access recovery OR fastboot but loops on "optimzing apps"
I had my US version OpO 64GB working with CM12 for quite a while, rooted and bootloader unlocked with TWRP (possibly 2.8.6) installed, then some months ago I tried upgrading to CM12.1 through CM updater. This failed miserably - The phone started bootlooping on "Optimizing apps n of N" - as soon as it finished optimizing apps, the phone would reboot and start optimizing again. Booting to safe-mode (Power + VolUpDown) also fails in the same way (though optimizing fewer apps).
I tried rebooting to recovery mode holding Power + VolDown but it just gives a quick buzz (vibration motor) at the "1+" screen and reboots. The same thing happens when I try to boot to fastboot mode with Power + VolUp. So I'm completely stuck. All the guides show being able to boot either to fastboot or recovery (soft-brick) or else the screen being completely black/unresponsive (hard-brick). My phone is neither of these!
I got frustrated enough that I've let it sit on the shelf for the past 6 months, but now I'd like to fix this. All help appreciated.
---danq989
Did you try clearing the cache and doing a factory reset ?
SpectreFang said:
Did you try clearing the cache and doing a factory reset ?
Click to expand...
Click to collapse
That's impossible for me to do since I can't get to launcher or recovery.
No acess to recovery?? Then better take it to service center... Atleast can u boot to fastboot mode or adb accesible then use oneplus one toolkits
---------- Post added at 11:34 AM ---------- Previous post was at 11:31 AM ----------
Install oneplus tool kit, while optimising apps it gets dectected by pc, just make it reboot mode & do reset.... Dnt worry this can be fixed, if all these seems messy then take it to service center
danq989 said:
I had my US version OpO 64GB working with CM12 for quite a while, rooted and bootloader unlocked with TWRP (possibly 2.8.6) installed, then some months ago I tried upgrading to CM12.1 through CM updater. This failed miserably - The phone started bootlooping on "Optimizing apps n of N" - as soon as it finished optimizing apps, the phone would reboot and start optimizing again. Booting to safe-mode (Power + VolUpDown) also fails in the same way (though optimizing fewer apps).
I tried rebooting to recovery mode holding Power + VolDown but it just gives a quick buzz (vibration motor) at the "1+" screen and reboots. The same thing happens when I try to boot to fastboot mode with Power + VolUp. So I'm completely stuck. All the guides show being able to boot either to fastboot or recovery (soft-brick) or else the screen being completely black/unresponsive (hard-brick). My phone is neither of these!
I got frustrated enough that I've let it sit on the shelf for the past 6 months, but now I'd like to fix this. All help appreciated.
---danq989
Click to expand...
Click to collapse
while things are loading, have u tried to hold vol up + power for 10 seconds or until the screen turns off and then hold vol down + power button until the oneplus logo?
Bradl79 said:
while things are loading, have u tried to hold vol up + power for 10 seconds or until the screen turns off and then hold vol down + power button until the oneplus logo?
Click to expand...
Click to collapse
Yes, just tried it. Same thing as described in my original post. When I hold power+volup the screen goes blank. I switch to power+voldown until the 1+ logo. At that point:
1. If I continue to hold the power+voldown key through the 1+ logo, the screen goes blank briefly, the phone vibrates once and reboots. If I continue to hold the power+voldown key, the vibrate&reboot cycle continues indefinitely
2. If I let go of either the power button, the voldown button, or both at or before the 1+ logo, the phone boots normally and goes to "Android is starting... Optimizing app n of 119). When the optimization finishes, the phone instantly reboots.
It's like the phone recovery is gone or inaccessible. Could this have to do with the phone tampering setting? As I said, I had this phone rooted and bootloader unlocked, working fine with CM12 for some time before trying an in-place upgrade to 12.1. That's when things went south.
---danq989

Pixel Stuck in Bootloop, ADB Unauthorized, Bootloader Unlocked

Hello, I recently came on a pixel phone to build and use lineageOS on. Upon rebuilding, I believe I performed adb sync wrong the device and damaged system. After that, my adb keys became unauthorized and I am unable to access the bootloader menu(I press power and volume, but phone boots into Bootloop). I tried the steps to get to bootloader menu, but the phone doesn't power completely off, and when I press the power button it gives me the launch screen saying press power to pause/continue boot, not allowing me to go into bootloader
My bootloop goes like this: Bootloader integrity screen(bootloader unlocked, cannot be verified) --> Google loading screen --> Android recovery. This shows 2 options with the message, "Can't load Android system. Your data may be corrupt. If you continue to get this message, you may need to perform a factory data reset and erase all user data stored on this device". The two options are to try again or data reset.
I press try again, and the same bootloop ensues, sometimes getting to lineage loading logo, but then back to the same recovery error regardless. If I press the buttons(power and vol up), to go into recovery, it just shows an android with a warning sign above it, giving a message saying "Error!" on the bottom. My adb on the computer shows as unauthorized, so I don't know how I can fix this. Google has said the warranty is expired and cannot do anything to help. Ideas to fix? Thanks for help in advance!
Use power and volume down (not up) to go into Fastboot mode. Then flash the stock images
NZedPred said:
Use power and volume down (not up) to go into Fastboot mode. Then flash the stock images
Click to expand...
Click to collapse
I tried that, but whenever I press any button, the phone is never turning completely off unless it dies. Even after that, it goes to the screen showing the secure boot integrity(Press power to continue/stop boot)
How can I completely shut off the device and restart it? And if system is messed up, will that leave my bootloader intact(I'm assuming so as boot is a different partition?)
mycalculations said:
I tried that, but whenever I press any button, the phone is never turning completely off unless it dies. Even after that, it goes to the screen showing the secure boot integrity(Press power to continue/stop boot)
How can I completely **** off the device and restart it? And if system is messed up, will that leave my bootloader intact(I'm assuming so as boot is a different partition?)
Click to expand...
Click to collapse
Does holding down the power button for 5-10 seconds turn it off? Or if you do that does it appear to turn off and then restart?
If that fails to turn it off, try just holding power and volume down for 5 seconds, and if the screen flashes (goes off and then on) let go of the power button but keep holding volume down and hopefully it goes into Fastboot.
That should work unless you have a dodgy power or volume button. The bootloader is completely separate to the boot partition, and the fact that it's doing anything at all suggests that it's still functioning.
Only other option I can think of is trying ADB commands when it's in recovery mode, e.g. adb reboot bootloader. However, if you have the stock recovery, that may not work.
NZedPred said:
Does holding down the power button for 5-10 seconds turn it off? Or if you do that does it appear to turn off and then restart?
If that fails to turn it off, try just holding power and volume down for 5 seconds, and if the screen flashes (goes off and then on) let go of the power button but keep holding volume down and hopefully it goes into Fastboot.
That should work unless you have a dodgy power or volume button. The bootloader is completely separate to the boot partition, and the fact that it's doing anything at all suggests that it's still functioning.
Only other option I can think of is trying ADB commands when it's in recovery mode, e.g. adb reboot bootloader. However, if you have the stock recovery, that may not work.
Click to expand...
Click to collapse
Thank You!!! It didn't work in the bootloop, so I had to let the phone drain its battery and shut itself off, then I was able to enter the bootloader and reinstall lineage. Thanks so much!
mycalculations said:
Hello, I recently came on a pixel phone to build and use lineageOS on. Upon rebuilding, I believe I performed adb sync wrong the device and damaged system. After that, my adb keys became unauthorized and I am unable to access the bootloader menu(I press power and volume, but phone boots into Bootloop). I tried the steps to get to bootloader menu, but the phone doesn't power completely off, and when I press the power button it gives me the launch screen saying press power to pause/continue boot, not allowing me to go into bootloader
My bootloop goes like this: Bootloader integrity screen(bootloader unlocked, cannot be verified) --> Google loading screen --> Android recovery. This shows 2 options with the message, "Can't load Android system. Your data may be corrupt. If you continue to get this message, you may need to perform a factory data reset and erase all user data stored on this device". The two options are to try again or data reset.
I press try again, and the same bootloop ensues, sometimes getting to lineage loading logo, but then back to the same recovery error regardless. If I press the buttons(power and vol up), to go into recovery, it just shows an android with a warning sign above it, giving a message saying "Error!" on the bottom. My adb on the computer shows as unauthorized, so I don't know how I can fix this. Google has said the warranty is expired and cannot do anything to help. Ideas to fix? Thanks for help in advance!
Click to expand...
Click to collapse
Similar problem when i try to flash pixel dust rom through adb sideload... After successful installation reboots to system through twrp it shows no os installed then after i cant get to bootloader only black screen shows no display and now on pc phone not detecting .... connect and disconnect sound is there but nothing on screen
LANDTESTER said:
Similar problem when i try to flash pixel dust rom through adb sideload... After successful installation reboots to system through twrp it shows no os installed then after i cant get to bootloader only black screen shows no display and now on pc phone not detecting .... connect and disconnect sound is there but nothing on screen
Click to expand...
Click to collapse
Is ur bootloader unlocked? If so, use twrp to perform a full wipe and install from twrp as well. Of you can't access trwp, and are in a bootloop, do the same thing I did: let the phone lose all it's battery, so it's outta the loop, connect the phone to a charger, then hold power and volume down. This should get you into bootloader mode where you can then use fastboot to flash twrp.
mycalculations said:
Is ur bootloader unlocked? If so, use twrp to perform a full wipe and install from twrp as well. Of you can't access trwp, and are in a bootloop, do the same thing I did: let the phone lose all it's battery, so it's outta the loop, connect the phone to a charger, then hold power and volume down. This should get you into bootloader mode where you can then use fastboot to flash twrp.
Click to expand...
Click to collapse
Oh so after that i can get to bootloader .....hmm let me try thanks bro
mycalculations said:
Is ur bootloader unlocked? If so, use twrp to perform a full wipe and install from twrp as well. Of you can't access trwp, and are in a bootloop, do the same thing I did: let the phone lose all it's battery, so it's outta the loop, connect the phone to a charger, then hold power and volume down. This should get you into bootloader mode where you can then use fastboot to flash twrp.
Click to expand...
Click to collapse
My bootloader is unlocked but phone not detected on pc only black screen nothing else.... Red light flashes whenever connect to charger

Nvidia shield tablet will note enter recovery mode

Some time ago a friend had an overheating issue with her Nvidia Shield tablet. The battery (original) was bulging but it still held a charge. I was, at first, able to enter the recovery menus but when I initiated the clearing of the cache (partition?) the process started but only ran for about 5-10 seconds before the device rebooted and went to a "no command" error. Since then I replaced the battery but still cannot get past the "no command". I am able to boot, through down volume + power, to the menu from which you can select reboot options, "continue" and recovery. When I try to initiate the recovery options, by selecting recovery options and then power, the device simply reboots and, yes, goes to "no command". Am I doing something wrong and/or any suggestions as to how I may recover the OS with minimal data loss would be most appreciated.
I also found that when I tried to connect it to my Windows 7 PC the device drivers fail to load so no third party recovery software appears to be of any use. MTB drivers failed to install?

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