Hyperpixel 4.0 (touch version) not working on RetroPie

so i have been playing on my RPI 3B with retropie for a bit, the touch screen arrived today (as the title says, a HyperPixel 4.0 touch version) and when i plugged it on the correct pins of my rpi3 and connected it via HDMI to setup the drivers, both the screen and my monitor show no signal. Does someone mind gving me a little helping hand?

Thanks,
Lorenzo.

Do you have anything else plugged into / hooked up to the GPIO?

Nope, the LCD occupies the whole 40 pin GPIO

OK, I asked that because the Hyperpixel makes use of / actually uses every GPIO pin.

Is the Pi booting up? Is the status LED flashing etc.
What are you using for a power supply?

The red LED is constantly on, the green LED doesn’t turn on AT ALL, when i put in a raspbian OS’d microSD it works fine, but retropie is just not booting at all. I also am trying to format the microSD but nor sd card formatter nor windows can do it (it says “format unsuccesfull”).

Ok, its not booting up which explains why you don’t get any image on your monitor.
If your going to image that card with Etcher, you don’t need to format it. Etcher will do all that for you.
I haven’t dabbled in RetroPie yet. I do believe the Hyperpixel installer is written for Raspbian.
If you install Raspbian, and then the hyperpixel stuff and it works, you’ll know you don’t have a hardware issue. Its just something in RetroPie that doesn’t like the Hyperpixel, it may be that its looking for and or expecting something else on the GPIO. Guest a guess on my part though.

I would like to just etch it and go too, it says though that the (16 GB sd card) is just 122 MB. When i try to format it, the pc just crashes.

If it was a Raspbian card there are two partitions. The Fat 32 boot partition and the Linux partition. Windows can’t see the Linux partition. Which is why it will nag you to format the card when plugged into a Windows PC. Doing that will just mess up your card and that format prompt should be ignored.
If you really want to wipe it in windows you’ll likely have to do a clean command from diskpart. Or go at it from disk manager.
Etcher should be able to wipe it no matter what’s on it if it isn’t defective. I’ve reinstalled Raspbain, installed Motion Eye over Raspbian and vice versa all without ever having to format the card first.
You may actually have a failed card? I have had one fail and it just showed some minscule amount of mb available. Nothing I tried ever recovered it, I just bined it and got a new card.