Ok, what if I were to cut the other main thick black wire on the left, that will definitely cut all video off from the screen but my question would be, would an external monitor connected the SVGA port still work?
You mean after cutting the wire? I can't guarantee it but I had a very old laptop where I completely removed the LCD screen and hooked it up to an external monitor which did work. The big problem is when hooked up to an external monitor you will never get into your BIOS settings because the external becomes active after the BIOS. So, if you plan on changing any BIOS settings, do it before removing the screen. You can confirm it by using an external and seeing if you can access BIOS before cutting the wire if that is what you intend to do.
Your computer's support site would have the service manual. Take a look at it.