[SOLVED] Gigabyte aorus b550i mini itx fault (short circuit?)

Feb 19, 2022
Hi, I'm doing a mini itx build with the following components : Meshlicious case, aorus b550i Pro, Ryzen 5600x, dual vengeance 16gb 3600 mhz ram, be quiet sfx l 600w psu, be quiet pure loop.
I have a problem. Please help...
I accidentally connected the motherboard wrong. The long connecter on the motherboard had the 8 pin connector that is supposed to go back to the psu initially going to the 12v connector, didn't work. Then I connected the p8 connection there instead and left the 8 pin disconnected and didn't I smelled a very slight burning smell, like a short circuit. I then realised that I didn't have the 8 pin going back to the psu, when I did connect it correctly the psu finally worked, but now the motherboard won't start up at all. Now whenever I plug the psu in and switched on, the psu fan and the radiator fans come on automatically, without even pressing the pc on button (which does nothing). I've tried shirting the two pin on the motherboard but that doesn't help. Have I fried the motherboard?
ps, ram is seated correctly and have tried with two different sets of ram,
Thanks for your help