At power-on the display shows the ROM revisions and the boot speech plays, but the game goes no further.

Game shows ROM versions and speaks, then nothing (burnt 3J1)

Cause: The 12-pin square 3J1 plug that brings all transformer voltages into the power supply has burnt, so the +5 V logic supply fails. The display still lights because it runs from its own plug.

Checks

• Unplug the game and inspect 3J1 and its board header for browned or burnt pins.
• The 6-pin 3J2 is a ground plug and rarely burns.

Fix

• Replace both halves of 3J1: the board-mounted wafer and the harness plug with new pins.

Unplug the game before working on the transformer, line wiring or power supply board.

Systems

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

Related tips

• Burnt 12-pin power supply input plug stops the game booting
• Burnt 3J1 square power input connector
• Resets from power supply connectors CN1 and CN2
• Burnt GI pin on the Data East power supply header: move it to a spare pin
• Power supply CN4 has no key: refit it carefully
• Power supply board versions are not interchangeable
• Power supply board versions and their +5 V filter capacitors
• Burnt GI traces on power supplies of Time Machine and earlier

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