Why does my ps3 turn on then back off? It’s not overheating

Older fat ps3 CECHK01. Runs fine doesn’t over heat. Question is when I turn it off and the red light is displayed and then turn the switch off in the back, after sitting a while when I flip the switch back on the ps3 automatically turns on with green light for about 2 sec and it’s enough for the tv to recognize a signal from the hdmi. Then shuts back off to red standby light. Works perfectly fine. Why does that green light come on for a second?