I have the MiFi 4510L and it keeps turn off several times a day. It goes from blinking/solid green to the yellow/orange showing it is off but charging or powering down. The battery symbol shows full charge as it is plugged in but the service strength symbol disappears (typical when charging but off). Anyone else having issues? I assume this is not a loss of signal but an actual problem with the device but I want to be sure.
Have you attempted a factory reset?