5-2 
 
5.3.2 Display Failures 
Symptoms  Possible Cause  Troubleshooting 
The display is 
blank or black. 
Cable defective 
1. Check if the cable between the display and main 
board and the backlight cable are correctly 
connected. 
2. Check that the cables and connectors are not 
damaged. 
Main board 
defective 
Replace the main board. 
Display defective  Replace the display. 
Images 
overlapped or 
distorted 
Main board error 
Replace the main board, or upgrade the main 
board with the upgrade software. 
Cable defective 
Check if the cable between the display and main 
board and the backlight cable are correctly 
connected. 
 
 
5.3.3 Button Failures 
Symptoms  Possible Cause  Troubleshooting 
Buttons do not 
work 
Cable defective 
Check that the cable between the keypad board 
and main board is correctly connected. 
Keypad board failure  Replace the keypad board. 
 
 
5.3.4 Battery Failures 
Symptoms  Possible Cause  Troubleshooting 
Battery 
cannot be 
charged 
Battery defective  Replace the battery. 
Cable defective 
Check that the cable between the battery interface 
board and power management board is correctly 
connected. 
Power 
management 
board defective 
Replace the power management board. 
Battery interface 
board defective 
Replace the battery interface board.