Video hardware testing, activating HDMI external display

I have a xps L501x with a cracked screen. in the cracked area I am seeing a flash green screen which tells me there is a video problem. I removed the internal video cable from the laptop and attempted to use just a external display (HDMI), but I am getting 8 beeps on post (which tells me the system is not detecting the internal display because I unhooked it).

I attempted to use the FN + F1 key on this model which is pictured on the keyboard to switch display settings but nothing happens. I also attempt to use an external keyboard via USB and that did not work either. I did remove the battery and press the power button for 30 seconds and power it back in but am still unable to get this external (HDMI) display working. Is it even possible to activity the external display on this thing during post?

Am I missing anything? Thank you.