Topics

It is not just the screen - the phone is not detected when connected to computer   When I connect 5v to the VBUS line it draws 0.5A for 1-2s, my impression is that it does not go through any initial first step when powered on

Lineage-23.2-20260803-NIGHTLY-pro1x with July 1st security patch installed smoothly via OTA. MindTheGapps16, and root was maintained.  Changelog: https://download.lineageos.org/devices/pro1x/changes

That could create a problem if off mode charging wasn't enabled using fastboot commands, except you said you charged the battery and it still won't boot.  Now I did have a problem with my old Pro1 in 2021 where the screen simply wouldn't com on at all.  I tried replacing the screen, but that didn't work. Luckily it was still 3 weeks before it went out of warranty and I was able to send it to Fxtec and they fixed it. Never told me what they did beyond replacing the screen, but I had the impression they had to do something else.  Not that any of this is of much help to you. Sorry.

I just let it discharge to zero by accident, no other special circumstances - definitely not water damage.

Too bad. Any special circumstances? Could it be water/moisture that got in and messed something? It sounds like a hardware failure of some kind to me. (Let us try to ping @CornholioGSM that got experience fixing PRO1/PRO1X)