Grey screen after booting

Hooked it up to an external monitor and it brings up the loading screen no problem, however the first attempt at loading my user profile resulted in a restart. My second attempt worked and loaded however only on the second monitor. What should I do from here?

We need to identify if it is a software or hardware issue. Or a combination. Are you running Sierra Beta? I like you to run Disk Utilities in Target Mode. Things I'm looking at are the hard drive IR cable (known issue). I'd like you to boot from a clean system from an external device with the internal hard drive cable disconnected.

I do not believe it is the IR cable as it has been recently replaced for a boot issue I had earlier this year. I should have disclosed earlier that this new issue happened after recently installing the newest El Capitan update 10.11.6. Also no I am not running Sierra Beta. Should I? I said nothing about the update because I thought it wasn't important till now.

Update: Had a realization that the IR cable is not the whole hard drive cable. Sorry for my amateur mistakes, I will now try taking removing the ir cable and seeing what happens from there

Update2: It is definitely a software issue as I am having no other problems running the computer. I cannot run my computer in target disk mode because I don't have another computer to hook it up to. My external monitor is the television to see if the computer would work. So where I'm at now is that whenI try to boot my computer alone I receive a black screen like my computer isn't started. Sometimes after a PRAM reset a grey screen that looks like the computer is distorted will appear but no images or login screen. However when hooked up to an external monitor its like my computer is running fine only the screen on my computer still acts like it does when I try to normally start it up after the update. This is a puzzling mystery.