At power-on the PIA LED lights and stays lit (or, rarely, lights and goes out), and the blanking LED never lights.

PIA LED stays lit and blanking never comes on

Cause: The game EPROM at 5C and/or 5B is bad.

Checks

• Reseat the EPROMs and check their sockets; try a freshly burned EPROM.

Fix

• Replace or reburn the EPROM(s).

Systems

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

Related tips

• Display EPROM version appears, then nothing more
• Game will not boot: GI on, little else happens
• A coil has power but never fires
• PIAs or the EPROM are never selected
• Program runs but the PIAs never respond
• All lamps come on, flipper fuse blows and the game won't boot: failed replacement NVRAM
• Flash lamp stuck on and melting plastics on L/R reversed games
• Two PIA exceptions when using the PIA test EPROM

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