Sometimes when the Daydream controller needs an update, or just in general, it will fail to connect. It will also not re-pair. The controller light will just fast flash (not the triple flash for low battery).

The stability of Daydream View VR has been dramatically improved with updates, but if you need to force-repair, things to try in order:

1. Reset and re-pair the controller
2. Uninstall and reinstall VR services and Daydream app.
3. Follow on screen directions to re-pair when entering the fresh Daydream app.

This helped when updating from Daydream controller software version 1.0.21 to 1.0.25.