Lenovo 13ACN5 Hardware Maintenance Manual page 59

Figure 37. Remove four screws and then remove the system board with I/O board cable
Screw specifications
M2 x L4.0
M2 x L1.8
Step 4. Peel off the tape and then disconnect the I/O board cable from the system board.
Figure 38. Peel off the tape and then disconnect the I/O board cable from the system board
Step 5. Remove the system board mylar.
Figure 39. Remove the system board mylar
Go to
https://support.lenovo.com/partslookup
replacement parts:
System board
System board mylar
Number of screws
3
1
to look up the Lenovo part numbers of the following
.
Chapter 4 Removing a FRU or CRU
53