Nonsense text on the display, a very fast-flashing CPU LED, and no attract mode or self-test.

Lithium battery leak damaging the CPU board

Cause: The lithium cell has leaked (less often and less badly than alkaline, but it happens) and corroded U6 and nearby traces.

Checks

• Look around the battery and U6 for corrosion.

Fix

• Clean and repair the damage, replace U6 if needed, and switch to a remote AA pack.

Battery residue is corrosive; wear gloves and clean it fully.

Systems

• Gottlieb System 3

Related tips

• CPU battery and socket parts
• Constant beeping, display blank, GI on
• Using a remote two-AA battery pack
• Battery reads 3 V but the game says it's low
• Fitting a CR2430 socket on the CPU board
• Getting past the low battery message
• "Control board error, Low battery or Bad U3 or U6"
• Battery error stays after a new battery

Source: Repairing Gottlieb System 3 Electronic Pinball Games from 1989 to 1996, Clay Harrell (pinrepair.com)