help please with already JB ps3

hi folks,could do with a bit of help with my already CFW PS3 as im desperate to get a shot of last of us etc before the new one comes out,its already been hacked but it needs updated and i dont know how im supposed to do it ! i bought the ps3 already hacked but its been gathering dust for a while

its on version 4.81 under system info

still has multiman 04.82.00 but it wont update when i try

firmware model says COBRA 7.52 COMPATIBLE on multiman

dont know much about cex or dex etc any...

help please with already JB ps3