Lenovo ThinkPad X390 Yoga Hardware Maintenance Manual page 47

g. PC cards
4. Turn on the computer.
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 nondefective FRU):
a. System board
b. LCD assembly
.
Chapter 4 Related service information
41