I went through the same issue with my Reverb - a first gen issue. That sent a new cable, didn't solve it - they replaced the unit under warranty, and that lasted about a year and then it broke again. Now its out of warranty, and I can't get to hp support because its out of warranty. I gave up and bought a Quest 2 with a link cable.
I actually think the problem might be inside the unit, where the short cable connects to the board. But I have no way to test that.