If it's just the supply that's fried who knows, might work. Can you not find other dumped electronics?

So I have some good news ... I managed to find AC-DC adapter that I could change the output voltage on and changed it to 15V and figured I have nothing to loose, so I connected it to the main intercom board, which then power up and the screen came on. Seems to be working 100%.

This means that either I have to take out the old SMPS board and just wire this adapter directly to the main board (I suppose not ideal) or I need to find a 220V to 15VDC PCB that will fit in the intercom shell/body (seems to be a bit of a low profile board, since the intercom is very flat).

Thanks for the help and I'll definitely try to find some other e-waste that I could use to learn while trying to fix it as well.