Recently my KPA (unpowered head) has become unresponsive after sitting idle for a few hours. I don't know long the unit had been in this state before discovering this. Fortunately it has not happened at a gig or at band rehearsal yet, but it is slightly worrying.
The unit was in browser-mode both times it has happened.
The first time, a couple weeks ago, it looked as if the brightness of the display and LEDs had been turned down to just a slight glow. The UI responded from the front panel, but attempts to change things didn't have any effect. The remote OTOH looked normal, and I could use it to switch between profiles and toggle effects. The unit was processing audio, but it sounded as if CAB-processing had been globally disabled. Had to powercycle to bring the front-panel back to life and audio back to normal. Could powercycle with the knob, but turning off was the only reponse from knobs.
Today the front panel has died. What seems like normal LCD-backlight is all there is, and no dials or buttons work. Can not even power off with the power/mode-switch. Like last time, the remote looks fine and is able to switch profiles and toggle effects. Audio sounds normal, including CAB-processing this time, at least for the limited set of profiles I've tested. Had to pull the plug to power-cycle.
The software version is 8.2.2 28378
It is a few years old (2015). Are there any batteries on circuit-boards inside that need replacing and could cause such behaviour? I have never experienced anything similar before. My unit is frequently on from early morning to late evening, idle for hours between uses as I find quite normal for a home-studio environment.
I've noticed that there is a new release out and will probably load that ASAP as I've been hit by the volume-loss-bug for certain rigs in the previous version. The change-log doesn't mention anything relevant to the problem I describe here so I don't expect the upgrade to fix my issue.