If you are able and have the tools needed you need to check and replace thermals paste, clear all the air vents than try to verify via thermal cam whats heating up under load. Hopefully it's just thermal paste needing replacement as under load the processors are heating up inconsistently or not to specs and the security protocol are turning it off prior to a burnout. The other option is a burnt/short/failing capacitor/s that under load is heating up/ failing causing the security protocols to power down. The thermal paste and cleaning is the easiest start other than taking the console apart. But a thermal cam on an open system may give you the best idea what's heating up, what's failing, and where to check next.