New build hangs on POST screen

[ThreeG]

Hey, my friend just finished new build but we have some difficulties booting this thing up. It appears to hang on POST screen with no specific messages, but I'll put more details below.

 

Here's the specs:

AMD Ryzen 7 5800x3D
Gigabyte B550 Aorus Elite v2 Rev 1.2 (BIOS version HB)

Kingston Fury 2x32GB 3200Mhz CL16

MSI RTX 3090 Gaming X Trio
Samsung 980 1TB M.2
FSP/Fortron Hydro G Pro 850W

All components except RAM and GPU are new. RAM works on previous config just fine though.

 

After pressing Power button there is one short beep, then there's Aorus' logo for half a second (the one showing keys needed to enter BIOS etc.), then it shows POST screen but there is only AMI logo in top left corner (no text at all). Fans and LEDs work just fine. 

What we've tried so far:
- checked all cables and connectors - everything is connected properly
- cleared CMOS 
- tried one RAM stick in every slot
- tried to enter the BIOS, but pressing Del doesn't do anything
- removing RAM entirely - in this case Mobo doesn't beep at all and there is no video output.

- checked BIOS version - Rev 1.2 of this mobo comes with BIOS that supports Ryzen 5xxx CPUs and there are no newer versions.

We still have RAM and GPU from previous build so we'll eventually test it with those, but I have the feeling that it's just faulty motherboard itself.

Any ideas what else we should check?

[191x7]

1 hour ago, ThreeG said:

Any ideas what else we should check?

... the CPU for bent pins?

[ThreeG]

CPU checked, no bent pins. But, after some more troubleshooting we decided to flash the Bios (using the same version, as there are no newer ones) via Q-Flash Plue and it worked! So yeah, apparently Bios was corrupted for some reason