Hello,
About the manual : read your PM
It's weird, but I do not see how the connection to the back of the A24-P2 (TC1) connector could burn something related to the SYS80B display.
In general, it is not necessary to reconnect the small RESET card because it generate more problems than it solves. The pinball can work very well without, and for a particular, this card has no use. It was only used in operation, to force a RESET of the pinball when the CPU card was hanged. Disconnecting this card while solving the problem, it is absolutely not necessary.
In SYSTEM 80B, the display works with commands and datas sent by the CPU (8-bit commands, read directly by the circuits 10939/10941). As a result, compared to a SYSTEM 80 / 80A the display circuit is much simpler.
2017-10-19_07h20_00 (resized).png
The data / commands are sent by the RIOT 6532 (U5 - not shown, on left of the picture). They pass through a buffer 7404 (Z16) and then into two latches 74175 (Z18 and Z20). The reset signal also passes through buffer 7404 (Z17) and this IC serves only for this purpose (not shared with matrix or decoding).
Maybe one of these circuits is roasted, but diagnosing which is difficult without a test bench or logic analyzer.
As you can see, there is no connection with the display and the TC1 connector, so I do not understand what could have been broken. If the decoding of circuit U5 (6532) is burned out, the CPU board will not work at all.
A trick also to try: invert the EPROM with the other Genesis that works. To be sure that the problem does not come from a partially erased EPROM.