Unless it's simply a loose connection (unlikely), disassembly & reassembly is unlikely to work.
BUT, to get you started, you'd disassemble from the underside, disconnect the battery & then remove the board.
This should get you started. https/www.youtube.com/watch?v=MyWYDS5YtdA
Realistically, removing the power adapter, disconnecting the battery holding the power button for ~30 seconds should perform the equivalent of a CMOS reset, and may have just as much chance of success, with less disassembly required.