Newbie with a fried 1200.

[rare_j]

Unplug everything from that board except the scandoubler/flickerfixer and the keyboard. Put your original roms back in.

Then plug your amiga into a regular tv using the composite port (the yellow one).

It may not be the roms you see, it may be something else not quite connected right.

Most important, Dont Panic.

[rare_j]

You might want to try to transfer the scandoubler off the old board and onto the new one, if that's not the bit that was busted in the first place, that is.
It looks like scandoubler (and possibly a flicker-fixer as well) made by DCE. Those two little boards just press onto the chips on the motherboard so you may be able to gently lever them off.
It means you can play games meant for a TV res on a PC monitor.