Question My PC won't POST and shows error lights on motherboard, please help

Apr 3, 2020
Here's my build:

PCPartPicker Part List:

CPU: AMD Ryzen 5 2600 3.4 GHz 6-Core Processor ($125.98 @ Newegg)
Motherboard: Gigabyte B450 AORUS M Micro ATX AM4 Motherboard ($85.99 @ B&H)
Memory: Corsair ValueSelect 16 GB (1 x 16 GB) DDR4-2133 Memory ($71.99 @ Newegg)
Storage: Hitachi 750 GB 2.5" 5400RPM Internal Hard Drive (Purchased For $0.00)
Video Card: Sapphire Radeon R9 380 2 GB Dual-X Video Card (Purchased For $0.00)
Case: Corsair 200R ATX Mid Tower Case ($0.00)
Power Supply: SeaSonic G 550 W 80+ Gold Certified Semi-modular ATX Power Supply (Purchased For $0.00)
Keyboard: Cooler Master CM Storm Devastator Gaming Bundle Wired Gaming Keyboard With Optical Mouse (Purchased For $0.00)
Total: $283.96
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2020-04-03 23:51 EDT-0400

Background: My PSU, GPU, SSD, HDD and case are from a previous build that went to green screen of death and didn't POST/fans stopped working.

So this build wouldn't go to post when I did a bench build. During this process I took off the stealth CPU cooler and rotated it and put it back on so it didn't block the first RAM slot, and I tiny bit of thermal paste got on a bit just near the edge of the CPU, and I wiped it off best i could. So after this it still didn't work, but the one thing that seemed to allow it to get to BIOS was me plugging in earbuds to the motherboard?? Like after it not working, I turned it off, plugged in earbuds to see if I could hear any error beeps, and it started and I flicked around BIOS.

So I built it in the case and hooked up my old Hard drives and it went straight to my old desktop environment, and I used my keyboard to navigate windows. So then I put on the case back panel, which required a bit of squishing since so many wires were running through the back, and I installed my WIFI card (I now realise i put it in the In the PCI-E X4 slot when it could have gone in the x1, yikes).

And it didn't go to POST, and the VGA light is on, and there is no signal on the monitor.

So when I start it now my motherboard flicks through the CPU and DRAM lights then settles on the VGA light, and the fans do this thing where they rev up then sort of abruptly cut back down to a lower speed. But sometimes starting previously it has just gone from DRAM light to VGA light, without doing the CPU light. And when I turn it off it again flicks through from VGA light to CPU and then DRAM quickly before shutting down. EDIT: When I started it up with hard drives plugged in I heard the HDD do the standard whirr to start up, and once even when the video didn't work my PC took a while to turn off, my guess as to why is that it loaded windows and had to go through windows shut down procedure but it just didn't show it cos the GU is broken?
Also additional info: I had the bottom left motherboard screw in way too tight for a bit, like it was bending it, which I only realised recently, this was actually stopping a line of yellow lights running down the left of the mobo from lighting up, and that lit up after loosening it.
I've re seated the GPU and RAM a few times, tried it without the hard drives, without GPU, with only one PCI-E power cable in my GPU and with both and with them switched around. Unplugged and plugged in the 8 PIN ATX 12V power cable, but I haven't unplugged the 24pin or the USB 3 one. I tried taking out the CMOS battery and shorting the positive and negative terminals. Gonna try with a new GPU.

I've probably made it worse, as I don't think it used to flash the CPU light before. Also when it started up the RAM was in the 4th slot (farthest away from the CPU), and I can't find which slot the RAM should be in in my motherboard manual.


The loud fan is the GPU fan, they are a bit out of whack. And in relation to the video below, the top left light is the CPU light, op right is DRAM, bottom left is VGA, and the bottom right which doesn't light up is the BOOT one : (
I would definitely send this in for repairs if it weren't for the lockdown.

I'm not sure what's going on, but any any advice would be really appreciated.
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