Chosen Solution
A while back (in the range of 1-2.5 years) my PS4 got hit with an overheating issue, where it overheated and shut down within a minute of turning on. I wasn’t really motivated to fix it at the time. I let it gather dust on a shelf, but a few days ago I replaced the thermal paste to see if that’d fix it. It turned on, but failed to produce a display. The LED stayed blue, and began pulsing after a bit. I could hear the fan going, and I was able to eject and insert a disc. I wasn’t able to connect my controller, however, and the power button would only turn the console off if held for 15 seconds. It typically stays on for a few minutes, before going into sleep mode, so it seems the overheating issue may be fixed, at least. It also doesn’t boot into safe mode. The second beep while holding the power button just never occurs. When power cycled, it DID show the “checking system storage” screen, with the bar at 27%, before it shut off again. I haven’t been able to reproduce this, however. Starting the console with the HDD removed doesn’t change anything, though I haven’t tried using an external drive. All that being said, any ideas what the issue might be? Dead hard drive? Funky power supply? APU solder failures? I forgot to test it before I replaced the paste, so it may have been damaged by the overheating, the time spent on the shelf, or by taking a physical impact. I may have also damaged something while replacing the paste. I did use an anti-static wristband and tried to be careful, but it’s a possibility.
Ok it still may be over heating. the screws that hold down the heat pipes etc need to be torqued to the same pressure. and did you tight them in a X or star pattern? if not and one is tighter then the rest it could be sitting a little off the APU. Not enough to see via your eye but enough to cause this. as for the rest you need to recheck all the ribbon cables and reseat them making sure they are square to the locking connector. if you are sure of these than you may need to buy a replacement PSU block which they run around $25-$45 USD and are readily sold on amazon
