Well, I rewired things and now nothing turns on. Should I take it to a shop, cause i'm lost.
I apologize as I have not read previous comments on this situation, but my input is below...
Were you just winging this or had you read a
couple of guides first?
Basically, what I would do, unplug everything on your PSU except the plug/cable going into the wall. Jump/short (connect a piece of wire, like a paperclip) between the green and the black wires on the 24 pin plug. If the PSU flips on (the fan inside spins up), you're good. If not, you might have fried your PSU.
Then follow the guide above, plugging in your 24, your 4/8 pin PSU plug, GPU plug, HDD plugs. If it doesn't boot, you might have fubared something and we will need to do further testing to check. Oh, take some clear pictures too, if you want us to double check things.
Everything is Murphy proof, so you most likely have not messed anything up majorly bad.