One of my older units (1.0.0) refuses to work (no files written when I deploy). I have flashed with the latest firmware (1.2.2), but when I try to configure or use the Time app. I get a reading of <3.6 v. The batteries are new, and if I put them in another unit I get a reading of 4.8 v.
That worked on default, but the recording is crackly. Fear we may have a mic problem too...
Try making a recording with the 'Enable low-battery cutoff' option disallowed. The problem might be the battery sensing rather than battery power itself.
Not that I can see, although it sounds like the exact same problem. Would they be externally visible?
Not if there are visible signs of corrosion I'm afraid.
This seems to be a symptom of corrosion in the original 1.0.0 version due to water ingress. It results from corrosion in the exposed vias (the plated holes that connect each side of the PCB together). In the 1.2.0 build they are covered by solder mask which offers more protection.