@paulguk, thanks a lot. This info saved me from sending my SA30 to the service as nothing else helped. My SA30 was bricked maybe due to an interrupted OTA Update.
During powering on, I pressed the “Service” button on the back of the device for about 60s with inserted USB stick with current SWU firmware image. The SA30 then took a long time to boot (different slower animation pattern in the display) and then after a few minutes came “Update completed Restarting”.**
Then everything worked fine again.