PS4 with very weird ON/OFF behaviours & won't sync with controller

This one is for experts only... very weird problems! :)

Current issues:

- After being unplugged PS4 will only turn on when waiting for approx. 5 minutes after power cable plugged back, otherwise no beep (only when pressing eject). Also turning off takes around 5 minutes untill flashing lights dissapear.

- PS4 doesn't sync with the controller anymore. I can still use it in Safe Mode but the Bluetooth connection doesn't seem to work.

I have already tried many suggestion across the web and just can't seem to pinpoint the issues even after opening the console (which didn't even look as bad as expected dust-wise). But i still think my issues are somewhat related.

Here's a quick rundown of what happened:

Almost a year ago I wasn't able to connect my PS4 through WiFi anymore (not a big issue as I use LAN almost exclusively).

Then last month my controller wouldn't turn no the console when pressing the PS button but still work normally after powering the console through the Power button.

And finally last week during gaming my PS4 controller just wasn't recognized anymore. It still works when connecting to PC (even Bluetooth).

After restarting still same issues so I unplugged the PS4 for a while and then it wouldn't turn back on. Then after waiting several minutes with the powercable connected it finally turned on but still wouldn't recognize the controller.

After opening and cleaning the dust off my PS4 I checked to see if the WiFi/Bluetooth antenna was fine and to my knowledge pretty much everything looked good. Tomorrow i might try to disassemble even more to check superficially if the motherboard and the chips look ok and also the PSU from the inside...

FYI I have also already rebuilt the database and also restored default settings. I haven't tried to initialize yet as I really don't want to lose what is potentially still on the HDD.

If anyone has ANY idea what the cause to these seemingly unrelated issues are or what I should be looking for when disassembling I'd be very thankful!