Happens to K2015 as well, if you try to upgrade firmware, gets an error flag on bottom of display.
Readings on most ranges are still correct however. But since K2015 has so much different functions, I didn't bother to find out, which one is wrong.
Have a cheaply acquired 2010 with A firmware here as well, self test isn't implemented there, but I don't dare to upgrade, since it probably looses calibration as well.