Terrible "graunching" sound when I put my foot on the brakes

More then likely this is the booster so I would replace it and retest. Here are the instructions from the manual on how to replace this.

However, if you have not inspected the brakes it may just be that they are metal to metal. So here are the guides that will help with this:

https://www.2carpros.com/articles/how-to-replace-front-brake-pads-and-rotors-fwd

https://www.2carpros.com/articles/how-to-replace-rear-brake-pads-and-rotors

Please run through this and we can go from there. Thanks