@tsebastiani @KornClown7
I managed well to unlock with subut and fastboot
(after generating my own unlock.bin and by saying
./fastboot_A1 flashing unlock_bootloader unlock.bin
in a linux terminal.)
After successfully unlocking:
Unfortunately, when I ran the UBPorts installer,
I put the JingPad into fastboot mode.
The installation process kind of started but stalled after a while
losing the USB connection.
After that I never again managed to get back to the bootloader menu,
even by closely following your instructions to overcome the loop
INFO: LOCK FLAG IS : UNLOCK!!
WARNING: LOCK FLAG IS : UNLOCK, SKIP VERIFY!!!
I did manage to occasionally start an adb shell and quickly say
reboot -f recovery
which, when the JingOS was still installed, would always safely bring me back to the bootloader menu.
Despite of not being able to enter the bootloader menu, I could even re-enter fastboot mode
by saying
reboot -f bootloader
in the adb shell.
From fastboot mode I could also boot into fastboot mode by saying
./fastboot_A1 reboot bootloader
I do not know, which other reboot options would have brought me into the bootloader menu,
but by now, the JingPad never ever even offers my a USB connection any more.
It just keeps cycling with the message
INFO: LOCK FLAG IS : UNLOCK!!
WARNING: LOCK FLAG IS : UNLOCK, SKIP VERIFY!!!
when USB-connected to power plug or to my Linux laptop,
or switches off after a few cycles when not connedted.
But now the JingPad always starts without vibrating!.
Before it always vibrated, when I pushed the power button,
while it did not vibrate when I pushed power + vol-down.
Did I now completely brick the device?
Will the battery be going down more and more?
Can I still charge it without an operating system installed?
Can/should I somehow re-flash the ROM?
What was exactly my mistake?
How can I fix it?
Did anyone take shots of the webpages like
https://forum.jingos.com/t/tutorial-how-to-unlock-bootloader-of-jingpad-a1/2718
before they took them offline?
Thanks for any replies or help.