Hopefully you meant swapped u17/u20 and not plugged in the wrong way that sometimes blows eproms.

9 is probable cmos ram bad... the original issue with the 7 may have been sockets and not roms. You can tell that sockets need to be replaced if you can rock or pull the eproms in them out without a tool, the retention is bad and they need to be replaced. (The sockets)

If you don't know how to solder on boards sent the mpu board to someone to have the sockets and chips replaced. The ram in question would be the one right next to U17.