Hints from my install:

Make sure the vario software number is the same as the display software number. Both display on boot up. It is possible that the vario software updates, and the display software does not update.

Don't turn the volume knob during software updates or while the vario boots up.

Check all your settings after software update -- time constants, altitude, etc. The software update can reset these with strange results. Bugs = 0 rather than 100% is especially interesting

John Cochrane