Boot loop after flashing Unihertz Titan EEA

[lietu]

Got myself a Unihertz Titan to try LineageOS on a device with hardware keyboard. It was already running Android 10 so I performed the following steps:

• Downloaded lineage-20.0-20230529-UNOFFICIAL-gargoyle_bgN.img.tar.gz from https://github.com/rumplestilzken/gargoyle_lineageos20/releases/tag/v1.2
• tar -zxvf lineage-20.0-20230529-UNOFFICIAL-gargoyle_bgN.img.tar.gz
• Enabled developer mode and USB debugging
• Turned on Enable OEM unlocking
• Connected the PC with adb and fastboot installed and allowed debugging

Then I executed the following commands

adb reboot bootloader
fastboot flashing unlock
fastboot erase system 
fastboot erase cache
fastboot erase userdata
fastboot flash system lineage-20.0-20230529-UNOFFICIAL-gargoyle_bgN.img
fastboot reboot

flash took a while but it kept saying OKAY for various parts:

Sending sparse 'system' 1/22 (131060 KB)           OKAY [  3.540s]
Writing 'system'                                   OKAY [  1.168s]
Sending sparse 'system' 2/22 (131048 KB)           OKAY [  3.542s]
Writing 'system'                                   OKAY [  1.131s]
Sending sparse 'system' 3/22 (131064 KB)           OKAY [  3.548s]
Writing 'system'                                   OKAY [  1.142s]
Sending sparse 'system' 4/22 (131056 KB)           OKAY [  3.547s]
Writing 'system'                                   OKAY [  1.087s]
Sending sparse 'system' 5/22 (131068 KB)           OKAY [  3.550s]
Writing 'system'                                   OKAY [  1.072s]
Sending sparse 'system' 6/22 (131036 KB)           OKAY [  3.552s]
Writing 'system'                                   OKAY [  1.239s]
Sending sparse 'system' 7/22 (131068 KB)           OKAY [  3.558s]
Writing 'system'                                   OKAY [  1.063s]
Sending sparse 'system' 8/22 (131060 KB)           OKAY [  3.560s]
Writing 'system'                                   OKAY [  1.118s]
Sending sparse 'system' 9/22 (131068 KB)           OKAY [  3.558s]
Writing 'system'                                   OKAY [  1.071s]
Sending sparse 'system' 10/22 (131056 KB)          OKAY [  3.556s]
Writing 'system'                                   OKAY [  1.140s]
Sending sparse 'system' 11/22 (131064 KB)          OKAY [  3.558s]
Writing 'system'                                   OKAY [  1.089s]
Sending sparse 'system' 12/22 (131052 KB)          OKAY [  3.562s]
Writing 'system'                                   OKAY [  1.147s]
Sending sparse 'system' 13/22 (131060 KB)          OKAY [  3.556s]
Writing 'system'                                   OKAY [  1.111s]
Sending sparse 'system' 14/22 (131064 KB)          OKAY [  3.553s]
Writing 'system'                                   OKAY [  1.087s]
Sending sparse 'system' 15/22 (131064 KB)          OKAY [  3.559s]
Writing 'system'                                   OKAY [  1.087s]
Sending sparse 'system' 16/22 (131032 KB)          OKAY [  3.560s]
Writing 'system'                                   OKAY [  1.277s]
Sending sparse 'system' 17/22 (131052 KB)          OKAY [  3.552s]
Writing 'system'                                   OKAY [  1.139s]
Sending sparse 'system' 18/22 (131060 KB)          OKAY [  3.549s]
Writing 'system'                                   OKAY [  1.107s]
Sending sparse 'system' 19/22 (131064 KB)          OKAY [  3.555s]
Writing 'system'                                   OKAY [  1.088s]
Sending sparse 'system' 20/22 (131060 KB)          OKAY [  3.571s]
Writing 'system'                                   OKAY [  1.137s]
Sending sparse 'system' 21/22 (117844 KB)          OKAY [  3.208s]
Writing 'system'                                   OKAY [  1.294s]
Sending sparse 'system' 22/22 (43932 KB)           OKAY [  1.207s]
Writing 'system'                                   OKAY [  0.418s]
Finished. Total time: 102.307s

Now I'm just stuck on an infinite boot loop. When it powers on there's the Unihertz logo, "Powered by android" logo, and very shortly later a very small notice appears saying

Orange State
Your device has been unlocked and can't be trusted
Your device will boot in 5 seconds

This screen stays for about 20 seconds, then the screen will turn off for about 5 seconds, and then it reapperas.

I tried pressing volume up, volume down, the programmable key on the left edge, power button, and the keys on the top row of the keyboard, in various combinations, both tapping them repeatedly, and holding for extended periods of time.

Rather unsurprisingly both adb and fastboot do not seem to recognize the device while it is in this state. On https://github.com/SolidHal/Unihertz-Titan-lineageos-microg/blob/master/README.md it says

recovery : power cycle and hold volume up. If you just get the broken droid, press or hold volume up some more, or possibly power + volume up.

Does not seem to work, but it also does say

note: unfortunately if you end up bootlooping for some reason, recovery is likely also inaccessible

and

Finally, this key combo is pretty finicky

Would appreciate ideas on what could be done to

1. Power off the device (my current plan is to just wait for the battery to run out)
2. Boot to fastboot again
3. Properly install LineageOS