MrElie wrotethe guy who told you the motherboard is wrong might be right. if you used the ps4 for a long time and for some reason the soldering melted a bit for some reason it could cause a short circuit and the ps4 board fried based on that.
my recommendation is first to stop tryin to take it to repair shops coz u will only make it worse.
take it to Sony which they have proper equipment to run diagnostics on the board and see what is failing.
i wish u the best of luck
For what it's worth, I had a Sony TV that wouldn't boot no matter what. It spent months at the Sony Center without them ever figuring out anything. Later on (like a year) I had already bought a new TV, but a friend saw my old TV and took it to a place (I can't remember where or the name). They fixed it in a week and I paid like 100,000 LBP I think.
Anyway, what I'm trying to say is "el sherke" don't always have the answer. More often than not, they're just glorified electricians.