Opposite grounding problem ?
I am having the same symptoms, I am unable to use 4 main button below the touch screen, but i am able to use the touchscreen fine. This happen 1-2 weeks ago, since I purchased it last June.
I tried one of the solution by lifting the silver pin and additional aluminium foil but it still did not worked, until I realized it was the opposite!!
Testing the same test as the youtube video.
If I put the HTC Sensation on the table, and touch the 4 button, it works.
But as soon as I touch the body
and touch the 4 button, it did not worked
I tried to isolate the grounding (literally with a cellotape), it still the same!
I think it is because there are still other golden pin that connects the body
I've factory reset, and tried different ROM. And even do a key test on the recovery mode. I conclude this is a hardware issue, and this grounding might be the issue.
For now, what i see as a workaround is to make sure that I did not touch the body when I use the button, by using a case (which I dont have yet)
I might add pics and vids later