Please don't waste any more time and mony on this, you have virtually no hope of solving any electrical problem on it for the following reasons:
Your model isn't an All Connect, Kalkhoff only made two Panasonic motored models at that time, the Agattu and the Pro Connect.
Panasonic policy with bike motors is to supply sealed for life with a two year warranty, no spares and no technical support.
There was no one 26 volt unit, they were supplied in different versions according to the pedelec manufacturers wishes. This sometimes meant even different circuit boards encapsulated within and incompatible handlebar units.
And as advised above, there are no software updates for these old models.
As you'll see on my Panasonic support pages that Saneagle linked you to, it's really only possible to repair some mechanical faults such as bearings failures
The 26 volt Kalkhoff on FB being broken for spares may not even have a Panasonic motor, since Kalkhoff stopped using Panasonic units after a while, changing to very different ones made by German manufacturer Daum. They had even more problems.
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