... and after all these days, I just realized that my firmware / keypad thinks that my mount is a GM 2000HPS (not 1000)!!! I looked into the keypad settings but didn't find any place to set this - I also looked if there is a way to reset the firmware to factory defaults - but that also doesn't seem to be possible.
Upon further investigation, the wrong mount is also displayed in the ASCOM driver and the MGBox software.
At this point, I contacted Tolga (from Tolga Astro where I bought my mount) and asked for help.
Update December 4th:
The support from 10Micron contacted me and asked to send in a log file from their mount logger app (I love it if companies have good logging software that you can run and they can use for further diagnosis). They also wanted to see a photo of the control box of the mount:
... this one also says GM1000!!! :-(
10Micron sent me a "Mount Remote" app that I can use to connect to the mount and they can use it to diagnose it from the distance. Very cool. Installation was almost straight forward. Initially the vcruntime140.dll was missing, but I could download and install this from Microsoft. Now, I'm waiting for 10Micron to connect and hopefully find out what's wrong.
Update December 5th:
The engineers at 10Micron analyzed my mount and determined that at some point a configuration file was corrupted during shutdown. Which isn't a problem as they get restored automatically. Only that the program restored the wrong configuration file (for a 2000HPS mount). So, now everything should work again. Yei!!!