Ok, the answer was
Tournament Solitaire.
The cabinet might as well be fresh out of the crate. Looks brand new, with the exception of EIGHT lockbar holes. The monitor has a great picture, and the coin door has a nice working bill acceptor on it. The coin door also has a slot for quarters, but there is nothing behind it, no mechs, no switch, even the holder for the mech is gone.
The keyboard problem WAS a battery issue. Unfortunately, even replacing the battery did not fix it (motherboard just constantly repeats the post).
I pulled the custom cards off the motherboard, and tried them in a spare 486 motherboard. Eventually after much tweaking I got it to come up. I didn't get it to fully come up though, it required a sound card on a certain IRQ and address, and the motherboard I used had the onboard video at that address.
Anyway, eventually I just set all the custom cards for the game aside, and just stuck a small form factor P2 400 in place of the original computer. This was also a pain in the butt, mainly because I had to guess at the trackball button connections. In a truly genius decision they didn't wire the buttons to the serial port along with the trackball, but instead they wired them to an ISA input card. Anyway, I eventually figured out how to wire the buttons through the serial trackball input PCB. At that point I slapped it back together, played a game of windows Solitaire, and then went to work.
Stuff inside that may be of interest to BYOACers.
ISA Rom boot card with ROMDOS and Tournament Solitaire installed on it. New roms could make this all kinds of useful. Stick this in a computer and the computer WILL boot from it.
ISA interface card. I believe that this is an older version of that massively expensive Happ controls CIB interface kit. It has a config rom on it, that I assume would have to be swapped out to take full advantage of the board (Tournament solitaire was only using a few inputs).
Happ trackball to serial port converter PCB.
2.5" Happ trackball.