Hi Everyone, I had the same problem with a V5200 and abandoned it for months after trying all sorts of suggestions (taping the holes, resetting...).
Picking it back today, I decided I wanted to know the reason and I found it and a solution.
Simply download the Plantronics hub (application) on your device. Scroll to the settings and turn off the ‘headset sensors’ and ‘HD voice’. The turn off the headset for about 5 - 10 secs and turn back on. Your device should work just fine. You can learn more here (under troubleshooting section) https://www.plantronics.com/content/dam/plantronics/documents-and-guides/en_gb/user-guides/voyager-5200-ug.pdf