Turn on the unit, keys activating without being pressed.
Press a key, there is no action.
Key switch: Normal situation; Do not press any key. Key circuit is electrical open. There is no key operation.
Press a key. Key circuit is electrically short. Key operates.
Analysis
Key short out operating as if it has been pressed.
Press a key, there is no operation.
The key does not operate.
Troubleshooting
Inspect key cable connections.
Test key operation.
Inspect key cable connections to the display.
If the key switch is normal, replace the display.
