The game boots and sits in attract mode (it will even start a game and the buttons make sounds), but the dot matrix display stays frozen on one audit/diagnostic screen and never changes.

Display stuck on the audit screen while the game runs: acid damage on the DMD controller

Cause: Battery acid had reached the DMD controller board mounted on the back of the display, corroding its header pins and nearby parts. Freshly repaired CPU and I/O boards don't help if this board was never checked.

Checks

• Confirm the CPU still runs (sounds, attract mode, buttons respond).
• Unplug the display and inspect the DMD controller board on the back of the panel for green or white corrosion around the header and the surface-mount chips.
• If you have a known-good DMD controller from another WhiteStar game, try it.

Fix

• Replace the DMD controller board, or clean the corrosion and repair the damaged header and traces.
• Corroded surface-mount chips may need to be removed, cleaned under and refitted or replaced.

Systems

• Sega/Stern Whitestar

Games

• Lord of the Rings

Related tips

• DMD stays dark while the game plays music: 74HCT240 on the display controller
• DMD shows the boot image then goes blank while the game plays: replace U201
• Three vertical lines missing on the DMD: glass cracked by a mounting screw

Source: Pinball Repair help group!! (Facebook group)