no gps anymore - Update 26.16 on Edge 840

This morning i updated my garmin before a ride (clever, i know). 

since then, i periodically get the message  GPS firmware updated successfully, but i dont get a stable gps signal anymore and I can't navigate / track. 

any idea how to fix it?

tried multiple factory resets. inspected folders with express - nothing changed it yet.

Update:

The gps version in the info shows 0.0