After 26.00 software upgrade sensors stopped working, after hard reset sensor hub shows 0.00

Ich antworte mal auf Deutsch: 

Hardwarefehler, den Kundendienst wolltest du sowieso kontaktieren. Uhr muss wahrscheinlich ausgetauscht werden.

Aber wer weiß ... vlt. fällt dem Kundendienst ja noch eine andere Lösung ein.

There are a lot of hardware problems following the 26.00 update ...
Garmin has a lot to worry about.

Same for me after 26.0. Whr and sns version 0.0. Nothing worked even hard reset so i let the watch turned off 3 days. Then i did again the sns onwatch update and it worked, for 1 day. Connected to my pc, ge updated sns fw again and it worked for a day. sns version returned to 0.00.

Will try to downgrade tonight.

strange enough after one night the sensor hub, bmx, whr... is now back to the original versions (22.09, 5.1.0,...) without me having done something actively. But sensors still don't work on the watch.

how can I roll back to the prior software release of the software to get my watch working again?

You can try the 3 button monkey grip.
Turn off clock
Finger 1 on the power button
Finger 2 on the start button
Finger 3 on the back button
Switch on the clock with finger 1, keeping the other two pressed.
At the first beep, release the start button and at the second beep, release the back button. After that, of course, also the power button.

Couldnt manage to downgrade, watch didnt react to old fw. If anyone has a file to share....

REceived this link in another thread :

https://my.hidrive.com/share/8z6g1evyp0#$/

Thanks a lot but watch still doesnt react. Even the fW from back date folder. I dont know why

I have the same issue. Sensors not working - Sleep, HRV, stress. Just heart rate. After switching off the watch it went dead and could not start it again. Done that with power key + flash light button (upper left button) and it started but nothing works. As if the battery is also draining faster. We need a fix asap.

Thanks Farronfor the monkey grip. That was actually what Garmin Support also proposed. 

Unfortunately no improvements. I find it strange, that every time I try again the hard reset the watch shows 0.00 for most sensors and after some time the correct release versions like 22.09 are showing. But it has no impact on the watch behavior. Sensor data is not processed. 

Even more strange: sometimes HRF and steps etc start working for some time (from less then a minute to up to 2 h) only to freeze up afterwards. 

After decates of using Polar watches I moved to Garmin last fall. Polar had frequent software instability when using. But I have to say that with Polar I never had a case that was not resolved by a Hard reset. If I ever get my fenix back to work I will for sure disable auto updates. 

If anyone (also from Garmin) finds a resolution please post.