yeah, the sound boards vary. I have High Impact Football and a couple MK1s and I believe the earlier Williams games use a different sound board that the latter Midway games toward the end of the hardware's life span.
not sure what stuff like Total Carnage runs.
anyway, OP, I promised I'd give you some feedback on what to look for.
your first board with the 2 bad banks of roms, I think you should check some basic stuff like the traces coming off probably the first and last rom sockets to see if there's any broken traces in the series. I highly doubt that 2 whole rows of roms would have dirty sockets, but I guess it doesn't hurt to look.
your second board with the black screen, I'd say if you're adept at handling a digital multimeter to check your voltages at the JAMMA harness OR rather check the JAMMA harness itself ... see if anything's cooked on it. black screen could be something as simple as the board not getting juice, which probably explains why you're not getting LED activity.
maybe get us some close up pictures; board #1 I'd say try to get the top and bottom of the rom sockets, and board #2 I'd say get a picture of the JAMMA edge or any other portions of the board that look like they may have got fried.
then maybe you'll get more guys with technical expertise to reply. I've never tried repairing any of these boards before, so I'm just throwing out some things to check.