With the test EPROM fitted nothing flashes and no PIA output changes.

Test program does not run at all

Cause: The CPU chip, or a fault in its clock, control, address, select or data lines.

Checks

• Replace the 6802 first.
• Then measure CPU pins 2, 4, 6 and 40: about 4 V (high).
• Pin 39 (clock), pin 5 (VMA) and pin 37 (E) are switching signals and should read about 2-3 V on a meter.

Fix

• A wrong reading on any of these seven pins points to the fault; trace its source on the schematic.

Systems

• Data East CPU Version 1/2
• Data East CPU Version 3
• Data East/Sega CPU Version 3b

Related tips

• CPU still will not boot after the basics
• Transistors, diodes and chips to keep for CPU and driver repairs
• A 6802 CPU chip works in place of the 6808
• Program runs but the PIAs never respond
• Checking PIA outputs with Leon's test EPROM
• Replacement CPU board keeps reporting a U38 PIA fault: try another 6802
• Two PIA exceptions when using the PIA test EPROM
• PIAs or the EPROM are never selected

Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Two, Clay Harrell (pinrepair.com)