MacBook Pro keeps randomly restarting and restarts during boot sequence

Hey everyone,

I recently got a late-2013 Macbook Pro Retina (15") that has a restart/reboot issue. This computer will work fine for hours and then out of nowhere turn off and restart. Sometimes, one restart is all it takes. Other times, it will restart itself during the boot sequence multiple times. When this happens, I can't even access the recovery drive.

The very first time I ran EtreCheck it called out heavy I/O usage. I restarted the computer and now every time I run EtreCheck and Apple diagnostics they come back with no errors or problems.

This issue has been happening for a while. The previous owner was told it needed a new hard drive and it was supposedly replaced (I have not verified - not sure if there's a scanner that can tell me if the hard drive is actually OEM or third-party). As far as I know, no other hardware has been replaced or modified.

I have done a clean install on the machine which helped for a while, but again, this computer can work for days and then randomly (maybe not randomly) go into the reboot cycle.

Any ideas I would greatly appreciate!