Veille countdown. What is that

Sounds like it could be low on power, and going into the standby (sleep) mode to save power. Did you try charging it?

I was at 100%

So perhaps you have let an actrivity running in the background, or just the activity menu, without starting one, and the countdown is telling you it is going to exit it - again to save power, because when the activity selection is activated, it enables also the GPS, higher monitoring sampling rate, and other features that consume power, so after a while, the watch will attempt to exit the mode, if not used. Similarly, it can happen when you pause an activity for a too long time. 

... anyway, you best ask this on the FR 45 Forum, since it may be specific to your device. In any case, it has nothing to do with the Garmin Connect Mobile Android app - that's what is the topic of this subforum. On the FR 45 forum, people will be able to assist you better, since they own the same device, which is not the case here, for most of the people.

Thanks, i didin't know. I ask for help on my cell phone and it bring me on this forum. I thougth it was for all the questions and help.