Lenovo ThinkPad Helix 20CG Hardware Maintenance Manual page 42

Verify that all attached devices are supported by the tablet.
Verify that the power supply being used at the time of the failure is operating correctly. See "Power system
checkout" on page 26.
1. Turn off the tablet.
2. Visually check each FRU for damage. Replace any damaged FRU.
3. Remove or disconnect all of the following devices:
a. Non-ThinkPad devices
b. Devices attached to the docking station or the port replicator
c. Printer, mouse, and other external devices
d. Battery
e. External diskette drive or optical drive
f. PC cards
4. Turn on the tablet.
5. Determine whether the problem has been solved.
6. If the problem does not recur, reconnect the removed devices one at a time until you find the failing FRU.
7. If the problem remains, replace the following FRUs one at a time (do not replace a non-defective FRU):
a. System board
b. LCD assembly
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ThinkPad Helix Hardware Maintenance Manual