ps4 has 6 second blod

i bought a ps4 that was supposedly not displaying on the tv but ended up working fine. i reset it, downloaded some games and a game update to it and all seemed to be working fine so i opened it tup to clean it out and replace the thermal paste and discovered the fan didn't work so i replaced that with a known good one and all was fine, or so i thought. i left it running a bit to see if it potentially overheated and it ran pretty cool so i turned it off and came back later and it was doing the 1 second blod when i turn it on. the 1 second blod then turned into a 6 second blod and now that's all it does. could the power supply be the issue or could it be something else