I am not sure if this happens to any of you before.
My KRC4 compact could not be shut down in a controlled manner and kept warning 'Battery or battery fuse defective - backup not possible' every time I turned it on. The voltage of the two was 10V and 3V respectively. I thought it was because of the low voltage that caused the problem so I replaced the two batteries to new ones which gave 12V to 14V.
However, the controller still cannot shut down in a controlled manner and the warning message was changed to 'Battery defective - load test failed'. I wonder if anyone has a similar problem? Thanks!