Venno

In ddu. You should selecting to not allow windows to auto install drivers after rebooting. Then install the driver from amd. See if that works.

Then I guess the only thing left is flashing your GPU

^ this is advised if your more of a beginner 
 

Still would try ddu and reinstall driver before doing anything with flashing the card. Its only a min or 2 min. 

Usually techpowerup are the ones that you would look for, for firmware updates
Gamer Nexus made a video detailing how to do it 

Did you try using ddu first?

It is most likely a firmware issue
Try flashing it with a consumer firmware and check if that helps 

That's the EFI Shell, part of your motherboard's firmware (The UEFI). Looks like the laptop does not/cannot boot into a simple UEFI interface. Use this shell to boot into an installed bootloader (Grub or Windows), which will in turn allow you to boot into your OS (*/Linux or Windows), and check for any updated UEFI/BIOS for that laptop on Acer's website.
https://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface#UEFI_shell
https://wiki.archlinux.org/index.php/Unified_Extensible_Firmware_Interface#UEFI_Shell

I would contact the seller to clarify what is installed and how to boot it as you said it's new and never worked
 
Checking the internet it looks like common thing with thios model and linux on it: 
https://forums.tomshardware.com/threads/cant-boot-from-usb-and-install-windows.3573389/
https://community.acer.com/en/discussion/580847/first-linux-boot-acer-nitro-5-an-515-54
 
Some solved it by installing Windows 10 on it but if you don't have the license i would try installing Linux Mint that is supporting Secure Boot.

Just a suggestion.
 
I would do a clean install of windows 10. If you have no problem with the hardware I would reinstall Linux. 

Who sold her the laptop?
 
What I meant was that whoever tried installing Arch (I think it was Arch, might've been something else, but it doesn't matter) did a horrible job of it.
 
Contact the seller of the laptop, try and get partial refund out of them. As for the laptop itself, just wipe the drive and clean install the distro of your/her choosing on it.

Check if secure boot is enabled  and try disabling it in uefi. There is also possibility they didn't install linux at all and are just calling it "Linux" cause it doesn't' have Windows installed

What Linux distro is it running? How did they install it? Who installed it?

I've properly connected the cables and double checked if they were, And it's quite weird that my GPU would overheat since my Big tower case has 7 cooling fans which are active at all times.
And in the summer they're on max speed too to keep everything within my PC cool.

Thanks for the info though!

I have a macbook pro and i pretty much destroyed my GPU due to overheating or something. I forced it to use the iGPU specifically and after a few weeks it was fine and started using the original GPU again. Right now i am typing this with my overclocked GPU.
 
I say use an external monitor connected to the GPU. Check if your main monitor's cable is connected to the GPU's output and not the motherboard's output.