Sounds like a connector issue - reseat the door connector - failing that, sounds like a switch matrix connector which are located on the RHS of the driver board.

Resets are common - will be the big cap on the power supply. Needs to be replaced with a 15,000 MFD cap, as the standard was 10,000MFD which is no good on a 3 flipper game. Interconnectors on the MPU/Driver board will need to be replaced.