Right after unplugging and reseating the backbox connectors, the dot matrix display shows only a few stray dots and a solenoid fuse blows.

DMD shows a few dots and a coil fuse blows after reseating boards: ribbon off one row

Cause: One of the ribbon cables had been pushed back on one row of pins off its header.

Checks

• Look along each ribbon cable header: every pin row should be covered, with no pins showing at one end.
• Confirm the display board's ribbon/bus cable is plugged in at both ends.

Fix

• Power off, reseat the shifted ribbon cable squarely on its header, replace the blown fuse with the correct value, and power up.

Systems

• WPC DCS

Games

• Corvette

Related tips

• J115 wire colors from Twilight Zone on (Corvette example)
• All flippers fire at power-up and blow the 50 V fuse: aux board ribbon upside down
• Lamp matrix connectors on the driver board
• Reseat the ribbon cables before chasing odd behavior
• Every coil and flasher locks on after reassembly: aux driver ribbon cable reversed
• F11 blows after a few games: shorted flasher leads on J122
• Flippers and ball launch dead, fuses look fine: F112 solenoid fuse blown
• GI connectors on the driver board

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