Question Cant boot a PC that booted fine yesterday! Dead MOBO?

[Dawis67_AE]

Hello.
These past couple of days have been weird. I built a PC around christmas and it was seemingly working alright. Some minor issues i could add is that sometimes the PC would be stuck on the loading screen with ASUS motherboard logo, but to fix it i would usually just hold in the power button and restart PC.

The PC is SFF but i managed to cram in a full ATX PSU in there. I didnt like how little room there was so i ordered the SFX PSU ( i would have done it right away but the country didnt have them in stock until now). Few days ago i went to change to the new smaller PSU. I also repasted the cooler to kryonaut and while doing so the CPU looked nice and well seated. After putting it back together, it wouldnt power up.

At first i thought that i hadnt put the front io power cable in correctly, but after making sure it was and after some further troubleshooting i discovered something very odd. The PC would turn on with the backpanel of the case removed, so naturally i assumed maybe the motherboard was touching something on the back, i checked and it wasnt. Everytime i would slightly press the metal part of the case behind the motherboard it would not power on. Sometimes i would have to pull on the metal thing on the back for the PC to power on, but once it did power on, no kind of flex didnt shut it down or anything.

Yesterday i decided to test if this was MOBO fault, so i got all the components out of the case, and placed mobo on a box and assembled everything. Then i proceeded to carefully flex the motherboard as i pushed the power button but everything seemed to turn on correctly (altho note, i didnt have GPU plugged in and the CPU doesnt have integrated graphics so i couldnt see any screen output)

Then i started putting everything back together. After putting it back together it was back to the same problem. I couldnt start the PC unless i remove the back panel. Now to make things worse, i cant get past the Asus ROG logo screen. (There are usually two screens with logo in the boot process. The first one is the logo with "Press DEL or F2 to enter bios" and the second logo screen is with a loading circle going around underneath the logo. )

Im stuck on the first screen with the "press del or f2 to enter bios", but even when i press those buttons, nothing happens. I tried to check the built in qled troubleshooting lights on my ASUS rog B550 i board. They dont even turn on. Only thing that happens is for a blink of a second, right after pressing the power button, the bottom LED flashes orange. Thats it, no further error indicators.

I really need your guys help and expertise here, as im profoundly confused. Im inclined to return my MOBO and get a new one as i think its broken, but i cannot be sure.

I have tried shorting the CMOS with 2 wires i had laying around, altho i couldnt find the battery on the board. Not even sure if its there.
I also tried putting my Memtest ISO usb into the USB slot to check maybe my M.2 windows drive is screwed up, but that doesnt seem to be the issue as nothing changes.

Parts:
AMD 5800x
MSI 3080
Corsair SF750
Asus ROG b550i motherboard

 

[RealBeast]

I would have also tested the GPU when you did the bench build, if it all worked you know that you either have a short or issue with the case front panel.

 

[Dawis67_AE]

I would have also tested the GPU when you did the bench build, if it all worked you know that you either have a short or issue with the case front panel.

Well, i couldnt hold the GPU in place and also flex the motherboard and also push the power button. I didnt want to break the GPU accidentaly so i didnt even plug it in. But the GPU should be working.

I was playing games and using the PC normally the day before. The only issue was that i had to take off the back panel to turn it on, due to the flex issue. After it was turned on, it worked normally. However ever since i moved here i do get the weird issue where the screen will turn black for 1 second, some minutes after booting into windows. This had no effect on programs and i didnt find any errors.

 

[Dawis67_AE]

Update: I again decided to take out the motherboard and test it. When out of the case, it seems to turn on correctly. That said i still cannot get past the "Press Del" boot screen. Its just stuck there, and will not respond to any key inputs. I shorted CMOS again, that didnt help.

I also noticed that the troubleshooting Qleds had now small black dots in them, which tells me they could have been shorted.