Hi Richard and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, consider/try the full hard RESET by removing the internal battery for a length of time and then replacing it (if have not been done).
Please click HERE to inquire for replacement battery.
The video HERE may shed insight on the replacement procedures.
This hard reset is both a test and a try of a fix. As it implies, a reset would force the unit to revert back to factory defaults removing glitches and config errors but would include memories, presets and user preferences. After a reset, the initial setup would have to be performed.
This is very critical - this reset however would not be corrective of an internal hardware concern; but it would be confirmed. In some instances, it may even expose/cause other issues.