In addidtion to this topic I've uploaded the original firmware but there's still no cigar there.
After following the reverting to original firmware I've managed to flash the original shelly dimmer 2 firmware to see if that would coorperate.
The Shelly firmware is on there and the device generates a WiFi network.
When connecting to this network by phone and opening the shelly app nothing happens..
The device is not found and can not be manually added by IP even when it is only connected to the shelly wifi.
When manually going to the IP I get greeted by the contents of the shelly:
As soon as I open the index.html.gz the device opens a shelly page but immediately starts complaining about not being able to fetch the device settings.
Clicking on the buttons of the web page to configure timezone, internet etc also seem to be broken as nothing happens / gets loaded. Only an error whe.n opening actions which is that no actions can be loaded.
Last but not least the calibration. Hooked up a simple light bulb and tried to open the calibration. it immediately states that it cannot execute the calibration.
One thing I do notice when plugging the device to mains is that the lightbulb goes on fully very shortly <100ms and after starts glowing very dim, and not being able to be controlled by the slider and/or power button.