Full reboots suggest you either have a bad battery or the contacts on the Jetpack touching the battery are bad or perhaps the USB port is loose/defective. In any case you should contact VZW and review the warranty support options that may remain on the device and use those up first.
If no warranty then replacement batteries can be purchased and tested fairly easily. However, anything else bad on the Jetpack such as the contacts, the USB cable port or something on the device itself will require replacement. VZW will offer you upgrade options if your warranty is already expired as a good way to proceed. Otherwise you can recycle the device and purchase a new or a refurbished device to get back on track.
