HP 2500C Series - Manual (Page 208)

Troubleshooting 8-8
LED or LCD
Sensor Error
The sensor has a problem if it activates continuously.
Possible Hardware Causes
§ Sensor problem
§ Bad PCA
§ Wiring or connector problem
Parts Required for Repair
§ PCA
§ Mechanism
Note
Whenever the back panel has been removed, make sure it snaps back into place
properly on putting back.