Remove The System Board; For 14-Inch Models - Lenovo 82RK00P5IX Hardware Maintenance Manual

"Remove the USB board" on page 46
Step 1. Remove the fingerprint reader cable.
Figure 43. Remove the fingerprint reader cable
Go to https://support.lenovo.com/partslookup
replacement parts:
Fingerprint reader cable

Remove the system board

For 14–inch models
Make sure the following FRUs (or CRUs) have been removed.
"Remove the lower case" on page 28
"Remove the storage drive" on page 32
"Remove the battery pack" on page 35
"Remove the memory module" on page 32
"Remove the heat sink" on page 40
"Remove the system fan" on page 41
"Remove the CMOS battery" on page 51
"Remove the Wi-Fi card" on page 44
Step 1. Remove two screws and then open the hinge.
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IdeaPad 3/IdeaPad 3i/IdeaPad Slim 3/IdeaPad Slim 3i Series Hardware Maintenance Manual
to look up the Lenovo part numbers of the following