PS4 Overheating Even After Being Cleaned

I’ve got a PS4 I got off of a friend who had it overheating. It ran extremely loud and turned off with a “PS4 is too hot” blue screen after opening a game.

I opened it up and found CHUNKS of dust in the heatsink so I fully took it apart (carefully) and cleaned it out and put it back together. The one thing I didn’t do is replace the thermal paste as I can’t find mine. (It did look a little crusty).

It still is doing the same thing, ramping up the fans to 100% even on the menu but the funny thing is when I put my hand behind it all I can feel is cold air.

Any ideas on what the problem could be? Replacing the thermal paste might work?

It’s the launch edition if that makes a difference.

Thank you!