Graphics card not working - worked fine before

About an hour ago the computer was working fine. After going out, coming back and turning it on, it would not display anything on the monitor.

I opened the case up and looked at what happened. Everything is plugged in correctly. I have removed most of the dust inside. The graphics card fan spins once and then stops upon powering it up.

I believe it is an AMD (Radeon HD?) R7700.

After looking online I tried replugging the PCI-E into it and nothing changed. It worked fine an hour ago, can anyone help me out?

UPDATE: Turns out it appears to be overheating as the only decent explanation. It refused to work for a good 5 hours, but after leaving for 3 hours and coming back it worked fine.

Update - still not working but when i reseated the RAM and powered it on it made beeping sounds and the fan spun - still no picture. Reseated again and nothing happened. (Back to square one)

It could be that it just died, do you have video out on the MB ?