I just have ran into the same problem as you i also tried to upgrade OS via usb but kemper wont even boot up did you find a fix
Same issue here. My Kemper was at 8.2 vers (I forgot if 8.2.2.28378 or 8.2.0.28009) and today I was trying to update to 8.5.6.30271. I put the update file in kaos folder, like always, and connected a usb stick. But, in this moment, Kemper shows the update screen, I put "yes" option and the update don't works. I tried a second time, but the same thing ocurred. For a moment, I believed that Kemper is exiting from some menus (bug of the last OS versions), but when I turn off my Kemper, the hell appeared. Now, my Profiler is freeze at starting. Not even shows "Initializing" text.
I'm Kemper user since 2016 and this year the OS updates have only brought stability issues. But what happened today goes much further 