It didn't work but this was expected. I started to desolder the bigger chips and to test them - all chips are OK!
So I decided to continue the torture (not sure who was the victim me or the motherboard

Here is the result: My first goal is accomplished: to take HiRes pictures of the empty board.
I scanned it with 1200 dpi and now I have both sides in 2x200 MB files (Windows BMP format).
Linear dimensions are preserved, so pictures can be used as template or for reference.
I think it would be helpful to place them somewhere in public (ideas?)
Next I'll re-solder everything back, replacing some ugly looking parts with shiny new components.
Second goal is: to have a "boutique" Oric Atmos (optionally working

I'll post pictures to show the restoration in progress.