Sounds like potential water ingress.
Have you checked your Bolt’s case for cracks or other gaps? I’ve had broken rubber on the right-hand buttons on mine, noticed it before water could get in (and put on a silicone case).
Could just be bad luck / any other cause, of course.
If you decide to pick up the Bolt v2: I did, and I think it’s a good upgrade, especially overall design and screen wise.