Make sure to wait at least 10 seconds after plugging in the micro USB cable provided.
If the LED still won’t start flashing in “knight rider” mode, please try with other micro USB cables that you may have at home (these are mostly used for Android phones).
If the FitBark still doesn’t turn itself on, unplug your FitBark and get in touch from the Support Chat in the FitBark Mobile and Web apps, letting us know that you’ve already tried to power the FitBark with other micro USB cables.