Lenovo ThinkBook Plus Gen 3 Hardware Maintenance Manual page 36

Figure 5. Remove the battery pack and pull out the cable
Step 2. Remove six screws and then remove the battery pack.
Figure 6. Remove six screws and the battery pack
Screw specifications
M2 x L3.5
Go to
https://support.lenovo.com/partslookup
replacement part:
Battery pack
30
ThinkBook Plus Gen 3 Hardware Maintenance Manual
Number of screws
6
to look up the Lenovo part numbers of the following