The game powers on with all zeros on the displays and goes no further.

Displays show zeros at power-on and nothing else happens

Cause: One of the three normally open tilt switches is closed (playfield tilt, plumb bob, ball roll), or a coin switch is stuck closed.

Checks

• Check the under-playfield tilt, plumb bob and ball roll switches are all open.
• Check every coin switch is open.

Fix

• Open or adjust the closed switch, then switch the game off and on again.

Systems

• Gottlieb System 80

Related tips

• Only "111111" in the player one display
• Dead CPU board: check the reset line first
• Game check-out, part 2: what a healthy power-up looks like

Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part Two, Clay Harrell (pinrepair.com)