New Build - No post

[GeoHandle]

Built a new computer and it won’t post. 
these are the parts:

CPU: Ryzen 7 3700x - stock cooler

GPU: Radeon VII

RAM: Patriot Viper Steel Series (2 x 8GB) 3733Hz

Motherboard: MSI MPG X570 Gaming Plus

SSD: Sabrent Rocket 512GB M.2 NVME 

Power supply: Corsair RM850x 80+ Gold

Case: NZXT H510

Problem:

when I start the computer it powers on and lights up, the fans spin, but there isn’t any output. The Debug LED for the CPU lights up initially, but then turns off and the lights for VGA and Boot very briefly flash on. After a brief pause the VGA light comes back on and stays on. Also while I used the power button on the case to turn the computer on, it doesn’t turn it off so I have to use the power supply switch to do that.

As well as this neither my mouse nor keyboard power on when connected to either the motherboard through the IO or through the case. Though when I plug in a charger with a light, the light does light up. (Both the mouse and keyboard are years old, so that might be a problem?)

 

What I’ve tried: 

According to my motherboard manual the VGA light is for the GPU, so I’ve reseated it multiple times and also tried putting it in the other slot. I’ve used both sticks and only one stick of RAM, and I’ve also used a preowned single 8GB stick of slower Corsair vengeance 2400Hz RAM. I’ve connected a HDMI lead to both the GPU and the motherboard itself, and also tried DisplayPort on the GPU. 
I checked the monitor was working using my laptop and it did.

Ive checked checked the mouse and keyboard were working also using the laptop and they did.

My power supply is modular so I’ve swapped both the cables for GPU and CPU, it only has one 24pin so I haven’t swapped that (I don’t know if that could cause the problem).

Initially I had a Samsung QVO 1TB SSD and a old barracuda 1TB HDD, I’ve disconnected both just in case.

ive tried updating the bios using a new usb but no extra lights indicated anything so I don’t know if that worked.

I also disconnected the power supply and used a screwdriver to jump the clear cmos.

 

EDIT: I've managed to dig up an old APU to put into my old system, works fine without the graphics card, doesn't work with it. So Graphics Card is definitely broken. I'd thought the problems I had experienced with the keyboard and mouse might have indicated a problem with the motherboard, but they did the same in an older system when using the faulty graphics card and worked fine in the same system when running on an APU, so at least it seems only one piece of hardware is broken.

[Juular]

8 minutes ago, GeoHandle said:

After a brief pause the VGA light comes back on and stays on.

That's pretty self-explanatory, your AMD room heater are faulty. Did you test it in some other PC ?

[GeoHandle]

14 minutes ago, Juular said:

That's pretty self-explanatory, your AMD room heater are faulty. Did you test it in some other PC ?

Haven’t had a chance. I’ll have to ask a friend to try it in theirs.