Ps3 Cfw Not turning on

Hello guys, so I have a Jailbroken Ps3 Fat model on 4.84.2 D rex and ive been having this problem with my Playstation when i turn it on it will turn on , like i can hear the fan running and everything but after like 4 seconds it will turn off. And it will do that about 4 times before the playstation actually starts to run. bu then the instint i get into a game The playstation turns off.... please give me help im really desperate at this point

-Ive already re installed thermal paste