Rig not Booting

[TheRealTerrance]

Just built a rig, and it doesn't boot, as the title suggests.
When I hit the power button, the PSU and GPU fans rev up then turn off again, while the CPU fan stays on.
The CPU is definitely working - I can hear the transistors and it gets hot - but it doesn't post.
I'm using an MSI Z370-A Pro, which has EZ Debug LEDs, and the CPU and DRAM LEDs flash in an alternating pattern, with a pause before starting the cycle again.
I was originally using 2 8GB sticks of DDR4 HyperX Fury RAM, but I tried swapping them out for a single stick of rubbish old unnamed DDR4 and the lights did something completely different: the VGA light lit up for a second, and the HDD light on the case also lit up, which it wasn't doing with the HyperX. Still didn't boot though.
My current working theory is that the two bent pins on the motherboard are the issue (why didn't you get to that earlier, dummy?), and I know you can bend them back into place but I just wanted to check that there weren't any other issues first.
I haven't been able to find any useful documentation on how the debug LEDs work, so if anyone has any ideas of what the alternating CPU/DRAM LEDs mean, that'd be helpful too.
Anyway, hopefully you lot can be of some assistance. 
Also while I'm here, the mobo doesn't have a mounting bracket for the stock intel cooler that I got with the CPU. I'll probably just buy a Noctua fan instead, but if anyone has any bright ideas to fix that without having to buy stuff that'd also be greatly appreciated. 

[TheRealTerrance]

Also just gonna post full specs here for reference:
Mobo: MSI Z370-A Pro
CPU: Intel i5 8400
GPU: GTX 1060
PSU: BeQuiet System Power 9
HDD: WD Digital 2.5" SATA HDD that I ripped from my old laptop (this is only temporary)
RAM: HyperX Fury 3200MHz DDR4

[Digideath]

8 minutes ago, TheRealTerrance said:

My current working theory is that the two bent pins on the motherboard are the issue (why didn't you get to that earlier, dummy?), and I know you can bend them back into place but I just wanted to check that there weren't any other issues first.
 

That is your issue. Yes you should have said that eariier. You've probably took out a memory channel or a sensetive line. You now have the unfortunate job of bending those pins back into place without breaking them.

[TheRealTerrance]

7 minutes ago, Digideath said:

That is your issue. Yes you should have said that eariier. You've probably took out a memory channel or a sensetive line. You now have the unfortunate job of bending those pins back into place without breaking them.

Alright time to probably break my mobo even more...