Ok, I discovered that the USB connection also produced EventID 51 warnings on my Windows 10 machine, with: "An error was detected on device \Device\Harddisk2\DR66 during a paging operation." This is an indication of a possible failing disk within the Clara.
I did had a clone image of the original microSD, and replaced that with a different microSD: no success, same errors. So perhaps the internal circuitry is failing. Connecting an USB cable makes the display now also flicker with "device detected". It is getting worse, and beyond my capabilities.
As the Clara still is under warranty, I did send it back for "repairs". We will see what they come up with
