PS4 Blue light help

Hi Guys, I opened up my ps4 to clean out the fan recently, playing MGSV would make the console sound like a jet engine I cleaned out the ps4 and put it back together and now when I try and turn it on it beeps, the light flashes on, then it goes dead I've narrowed it down to the psu being faulty or dead, or the fact that some thermal paste came off the APU Can I have some opinions as to what else it could be? I've tried different plugs, sockets etc and the only thing I think I can do now is open up the psu and look