My ender 3 v3 ke stops printing

My ender 3 v3 ke stops printing part way through a print. I have changed stl.s changed the filament, ensured the level and nozzle are ok, put in a new heater head in with no result. The print stops and then when i try and restart it it shuts down and when it resumes it starts at a higher point. Any suggestions? My only thought now is to re-root it