FP4 replacement screen flickered then went unresponsive

In short
My FP4’s screen went off after it started flickering while watching videos. Phone worked flawlessly since I replaced the screen, camera and battery with brand new module 6 months ago and installed a screen protector bought from Fairphone.
Note this first diagnostic, parts ordering and repair took many weeks as no local repairshop wanted to do it and the closest FairphoneAngel was 250 km away. Having the phone unusable again 6 months later is all the more annoying: I use an e-SIM card, and can’t be called at all.

In details
Phone worked flawlessly untill Sunday when the screen first flickered while watching a video, but gently pressing the screen had the display works fine again. Then no issue for a couple days. It flickered again on Wednesday and no manipulation could help incl. removing & reinserting the battery.
Looking closely with the phone powered, one can see the screen is very lightly and uniformely illuminated with a dim blueish light.

Disassembling my phone carefully revealed all connectors firmly in place and no peculiar damage or even dust. Except for a loose small copper part that you can see in attached photos. I used “wind” (dunno the English term) and a dust-removal soft cloth before assembling it back, with no change at all.

FP4 Screen front:

FP4 Main module, frame:

FP4 Screen rear and smaller modules:

FP4 Loose copper part:

By any chance do you please :

  • have some idea what or where the small copper part may be (belong)?
  • note something I missed?

EDIT: title.

As no one seems to be able to help I’d purpose you contactsupport .