Vaillant ecoTEC PLUS F29 Error Code: Troubleshooting Power Outage & Water Supply Issues

We had a pretty long power outage today. When he came back, the error code 29 + flashing tap icon appeared on the stove. It seems to me that I had it before and that it was due to the lack of water supply during the breakdown ...

I tried to turn it on to no avail. Please help

Error F.29 in Vaillant ecoTEC boilers concerns the failure to detect the flame during operation. Ie. During the burner operation, there was a gas failure and then the boiler could not start. This could also mean a damaged gas valve or electronics.

Switching the boiler off and on again does not help. You have to reset the boiler with the "failure reset", that is with a gray button with a symbol of a crossed flame. Then the boiler goes through a test procedure and if everything is ok, it tries to ignite the burner. Further unsuccessful attempts cause the crash again and error F.28. And this may mean a visit to the website because there is nothing you can do yourself.

Thank you for your help. It turned out that there was a gas failure after the power failure The gas was probably cut off automatically due to a power failure.