A testrom will certainly provide you insight about what your CPU board is doing or not doing. The Reset signal is just a DC signal and easy to measure with a multimeter. Reset is active if pin 40 is low, 0 volts. The board will not boot in this case. You will need a Logic probe or oscilloscope to check the clock signals.
The PIA LED will just be stuck if your board isn't booting. You can check if the diagnostics are working: remove the SRAM -> turn the game on -> the PIA LED will flash one time. If this diagnostic signal is working it tells you the board is at minimum starting its diagnostic routines; also telling you the reset signal and clock signals are probably okay.
AMI chips are unfortunately a common failure point. It is worth to try another 6802/6808.
Also check the IC sockets for the CPU, ROMs and SRAM for corrosion due to a leaking battery. At IPDB.ORG you will find the gamerom binaries.