Lenovo ThinkBook Plus Gen 3 Hardware Maintenance Manual page 52

Figure 29. Disconnect cables
Step 3. Remove three screws and remove the system board.
Figure 30. Remove three screws and remove the system board
Screw specifications
M2 x L2
M2 x L3.5
Go to https://support.lenovo.com/partslookup
replacement part:
System board
46
ThinkBook Plus Gen 3 Hardware Maintenance Manual
Number of screws
1
2
to look up the Lenovo part numbers of the following