iMac 2011 That Won't Boot

[gaza4]

Ok so let me pre-empt this by saying this was a dumpster find (glass was smashed but the screen behind is fine) so it may be far beyond repair but lets give it a go anyway

So its a mid 2011 27" iMac. When I found it it had no RAM so I salvaged a 2Gb and a 1Gb stick out of an old laptop (could this be causing any issues maybe? I'm not even sure what slots to populate first or if these sticks are compatible!!!)

The machine powered on but all i was getting was the Apple logo on a grey screen.

I reset the SMC and NVRAM, one of these steps got a loading bar to appear. It fills about 3/4s then both the logo and bar disappear. After a few mins the machine restarts itself.

I tried using Internet recovery but that didn't get me anywhere and I cant seem to get it to boot into either recovery or safe mode

I also removed the HDD and connected it to my girlfriends MacBook Air but that wouldn't load it either

 

 

At this point I figured the OS is probably damaged so it just needs a fresh install but a friend recommended i try load Linux to rule out any other issues

Downloaded Rufus and Lubuntu and loaded it onto a USB stick. I get to a black screen when I'm prompted to start Lubuntu and then the screen just goes black. I have tested the USB on the MacBook Air and it works fine

 

I think I have exhausted all my options at this stage and I just dont know enough about Macs to take it much further so if anyone has any suggestions I'm all ears, otherwise its going back to the dump!!!