For The 17-Inch Models - Lenovo IdeaPad 3 Series Hardware Maintenance Manual

Figure 48. Remove four screws and open the right hinge
Screw specifications
M2.5 x L5
M2.5 x L3.5
Step 3. Remove the system board.
Figure 49. Remove the system board
Go to
https://support.lenovo.com/partslookup
replacement part:
System board
For the 17–inch models
Make sure the following FRUs (or CRUs) have been removed.
Number of screws
2
2
to look up the Lenovo part numbers of the following
.
Chapter 4 Removing a FRU or CRU
61