My MiFi Liberate will not turn on. It is new and I've used it once or twice, so I know it has worked. It is charged. The battery is placed correctly inside. Also, when it is connected to my computer, there is no response and the computer doesn't recognize it.
Have you tried to use a different micro USB charger? If that doesn't work, you should contact AT&T's Tech Support at 1-800-801-1101 to possibility have it replaced. In my experience, its usually a dead battery and can easily be fixed.
If you bought your device from a Company Store and it has been less than 14 days, you can return it and have it exchanged. If you bought it from a local dealer, or national retail (such as Best Buy) you can check with their return policies and get a replacement.
Hope this Helps!
*I am an AT&T employee and the postings on this site are my own and don't necessarily represent AT&T's position, strategies or opinions.