Is your GPU failing? And you got no tools to use? I have a solution based on my experience, and this is the story.
I had this 4 to 5 year-old GPU which I am still using right now (2019-06-15). It failed to work and I got no other tools to use. So I tried something base on what I learn about GPUs. If heated on some degree the cpu/chip in it will work on some level.
So the solution:
1. I remove the fan or cooling system I am using on it. And assemble it in to my motherboard.
2. I open the PC/Unit, and wait for 5 to 10 secs. then shuts down the PC.
3. Then open the PC again, and wait for the beep sound that indicates it's powered on. And if it didn't open in your first try, just do the #2.
4. If it opens, power off your PC, remove the GPU -> reassemble the Cooling System -> Assemble it into Motherboard
-> Open the PC and it will work again. Note: If the pc is powered down and you are going to remove parts in it. Don't forget to remove the cord from the outlet.
Also, if you are doing the #2 again, let the GPU cool down a little bit before trying it again.
This solution works on mine. I hope this will help someone.