Hovatek Forum DEVELOPMENT Android UniSoC Tablet SC7731 stuck on bootloop due to vbmeta flash via fastbootd
Try our Online TWRP Builder..its free!
Can't login? Please, reset your password.


UniSoC Tablet SC7731 stuck on bootloop due to vbmeta flash via fastbootd

UniSoC Tablet SC7731 stuck on bootloop due to vbmeta flash via fastbootd

alee_
alee_
alee_
Newbie
3
21-06-2024, 01:03 AM
#1



Hello, I may have bricked my tablet and I don't really have a way to access the bootloader. I have a tablet that has a SC7731 as processor, I followed the steps on this post to unlock the bootloader, that was a success, then I wanted to flash a GSI, specifically the AndyYan's LineageOS 18.1 (Android 11) GSI, however the problem was that I didn't had the vbmeta from the stock firmware because I can't extract the .pac file and there isn't really an official (or unofficial) file for it, it was then when I discovered DSU, I sideloaded the GSI, it booted up just fine, then I restarted adb as root, which gave me access to "/dev/block/bootdevice/by-name/" I thought it was a good idea since there was both variants of vbmeta and boot for A and B respectively, just in case I checked this post to make sure the signature was the same, the binary data was the same, however the partitions were completely different (probably that was it), I thought since the signatures were the same then it would be fine to use the signatures provided in the post, I followed the instructions to create the custom signed vbmeta and then tried to flash it, it stuck on "writing", I already faced that problem before with an empty vbmeta file, to fix this I read that I had to use fastbootd if it froze, I booted into fastboot with fastbootd and this how it went:
Code:

ubuntu@ubuntu:~/Downloads/modified_fastboot$ ./fastboot flash vbmeta vbmeta-sign-custom6.img
2yesaraw0x10000000target reported max download size of 268435456 bytes
sending 'vbmeta_a' (1024 KB)...
OKAY [  0.038s]
writing 'vbmeta_a'...
Flashing succeededOKAY [  0.261s]
finished. total time: 0.300s


Rebooted into system, now I'm into a bootloop that lasts about 1-2 seconds, sadly I'm not able to boot into the recovery, fastboot, or bootloader using the volume combo (I don't know why though.), and to make it worse, I had the tablet connected to my laptop, and before booting into fastboot I saw that it had 100% battery, now it's slowly dying, the screen starts to flicker now, its kinda warm, I can't turn it off, adb and fastboot won't work, even if I hold down the volume combo I'm not able to get through the "INFO: LOCK FLAG IS : UNLOCK!!!", at least before it displayed "WARNING: UNLOCK SKIP VERIFY!!!" (or smth i don't remember) now it turns off before that, intriguinly however after 2-4 restarts while holding down the volume combo the screen turns off for about 30 seconds (but adb and fastboot don't work anyways) before going into bootloop again. Any help would be appreciated! Thanks in advance! (Ironic, the brand is called "Advance".)
hovatek
hovatek
hovatek
Administrator
49,634
21-06-2024, 09:40 AM
#2
(21-06-2024, 01:03 AM)alee_ ..Any help would be appreciated! Thanks in advance! (Ironic, the brand is called "Advance".)

You'll need the firmware as things stand. It was risky enough flashing a GSI without the pac file but you should've stopped there since you already had root then done a full dump using DD commands so you at least have a dump (though not in .pac format).

Provide the full model name for reference
This post was last modified: 21-06-2024, 09:42 AM by hovatek.

Note!
We have a reply schedule for Free Support. Please upgrade to Private Support if you can't wait.
alee_
alee_
alee_
Newbie
3
22-06-2024, 02:33 AM
#3
Well, I extracted the vbmeta.img and boot.img from root using dd, I really don't know what went wrong, plus it was a dynamic system, thus I wasn't really flashing anything onto the main thing. Anyways here is the full model: Advance Prime PR6152; CPU: SC7731 (4 cores)
alee_
alee_
alee_
Newbie
3
24-06-2024, 01:27 AM
#4
(21-06-2024, 09:40 AM)hovatek
(21-06-2024, 01:03 AM)alee_ ..Any help would be appreciated! Thanks in advance! (Ironic, the brand is called "Advance".)

You'll need the firmware as things stand. It was risky enough flashing a GSI without the pac file but you should've stopped there since you already had root then done a full dump using DD commands so you at least have a dump (though not in .pac format).

Provide the full model name for reference

Just for further reference, here's what I've done while in the DSU with root.

Commands executed in the DSU:

Command for extraction:

for file in *; do
    if [[ "${file}" = vbmeta* ]]; then dd if=/dev/block/bootdevice/by-name/"${file}" of=/storage/emulated/0/Download/"${file}".img ; else continue ; fi
done

adb pull /storage/emulated/0/Download/

Locations:
1: /dev/block/bootdevice/by-name (I used this one)
2: /dev/block/by-name
Misc (While in DSU):
getprop ro.boot.slot_suffix => _a
echo $PARTITION => boot_b

Also, here are the files:
https://dl.dropbox.com/scl/fi/xm3958srzz...wczbf&dl=1
This post was last modified: 24-06-2024, 01:35 AM by alee_.
sabahlclinton
sabahlclinton
sabahlclinton
Newbie
1
Today, 04:35 AM
#5



i'm on the EXACTLY SAME SITUATION with moto e13 after flash vbmeta with disable verity through fastbootd (because fastboot was frozening) now my phone just restarts on bootlogo every time Sad my phone is dead?
Users browsing this thread:
 1 Guest(s)
Users browsing this thread:
 1 Guest(s)
YtWhTl