2014 Mac Mini keeps restarting

Hi,

I have a Late 2014 Mac Mini that has started to crash and restart.

I noticed the Mac was warm so I turned it off and put an ice pack on it and left it for twenty minutes.

When I turn it back on it keeps restarting, gets to the end of the Mac OS loading screen then turns itself off and restarts again and does the same process.

If it does reboot back into Mac OS it will crash and restart the whole process again after a few minutes.

This is the only Apple hardware I own and I need it to work.

Can anyone come up with any reasons that it keeps crashing and any way to fix it?