HP ProBook 645 G4 Maintenance And Service Manual page 58

2. Remove the 14 Torx T8M 2.5×6.0 screws that secure the frame to the computer.
3. Remove the following screws that secure the frame to the computer:
(1): Two Phillips M 2.0×2.5 screws
(2): Five broad head Phillips M2.5×2.5 screws
48 Chapter 6 Removal and replacement procedures for Authorized Service Provider parts