3 day old build with GA-Z170X Gaming 7 not powering on. No fan, only light.

[notsonic]

I just built the following PC:

Cpu: Intel i7 6700k Skylake

Mobo: Gigabyte z170x G1 Gaming 7

Cooler: cooler master 212 evo

PSU: evga 850w gq

GPU: old MSI R9 290

Case: corsair carbide r100

Drives: Samsung ssd, WD black HDD, lg DVD-RW.

It worked totally fine for about 3 days. Played Doom, let it sleep etc, no issues.

Today I go to wake it up, my mouse and kB light up, but it never turns on.

So I unplug it and plug it back in, only the light on the power button for the case and mobo come on. No fan activity no HDDs spinning, nothing.

I've disassembled it to just the mobo, ram, cpu, and cooler outside the case, tried two power supplies, same thing. Removed the ram, same thing. Removed the cpu and cooler, same thing.

I'm not sure what to do from here other than replace both the mobo and cpu.

[ElectroStingz]

Hello,

If you use only the motherboard (you seemed to have done this without the fan)
- No RAM
- No CPU

Just connect the CPU FAN and PSU, try to turn on what happens?
If nothing (CPU fan does not spin) = dead motherboard <RMA it.

[notsonic]

I pulled the bios batter and it boots up now!

What the hell would cause that?