Console auto shutdown issue

Hello everyone, I have PS3 Slim with Hen 3, I was on 4.84 and it was working fine, I formatted it then upgraded to HFW 4.85 (installed it twice) and added hen again, from time to time the console shuts down all of sudden with no red light on the power button until I click on it again it becomes red then another click to power it on.
How to fix that I believe it's not power supply issue since I had no issues on 4.84 like five days ago.