Lenovo Legion Y540-15 Series Hardware Maintenance Manual page 52

Figure 36. Detach the 6 connectors
Step 2. Remove the 6 screws that secure the system board to the upper case.
Figure 37. Remove the 6 screws
Screw specifications
6
M2 x 5.0
7
M2 x 3.5
Step 3. Remove the key-lock bracket.
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Hardware Maintenance Manual
Number of screws
3
3