a careful application of heat should be enough to soften the glue and with a razor th=o pry open the case minimal damage can be achieved, the clips holding the plastic parts together will likely break but when reassembling use a strong glue and lots of clamping force and they should hold up fine

great but how do you fix the buttons? all of my parts are brand new but this is just a disassembly guide

This is not the G74SX, there is no back panel by the vents, it is a solid plastic bottom piece. Please edit the title of your guide to reflect the correct model.