Stuck on restore screen, cannot enter DFU

Hi, I have this A1934 on the table right now, it got fully submerged a few months ago. Since that I was told it's stuck on the restore screen, which I can confirm, no relevant data to save, so my immediate idea was to do full DFU recovery but for all I try (even assisted ReiBoot mode!) it always go back to the restore screen. It is not possible to do up/down/power restart either. I opened the device, it had two small water droplet marks on the chassis, far from any components. Down to the logic board, no visible water damage or oxidation, with exception of USB-C connector, outside part had heavy oxidation deposit. I cleaned it but it didn't change device's behavior a bit. What should be the next step?

(While describing this it occurred to me the power button could be faulty/oxidized too, because I have no reaction to it being pressed. Will look into it now too.)