Fitted a new SN750 in a 2015 MacBook Pro and performed a fresh install of Monterey via the online macOS recovery.
Mac boots from power off within a few seconds, no errors, performs perfectly, and powers down fine too. But, if a restart is performed, the Mac hangs on the POST.
Screen is black (but LCD back light is on), no errors, no sounds, no logo. Verbose boot mode shows the macOS shuts down fine but it doesn’t seem to be getting past the POST on restart, there’s nothing on screen to indicate why.
Conducting a PRAM reset seems to fail because nothing happens. SMC reset hasn’t helped.
Fitting the old Samsung drive or the original Apple drive restores the ability to restart. So it seems to be the SN750 that’s causing the problem.