I would do as Sachin suggests, reflash the entire tablet (not the internal memory card) and don't restore anything from a backup. See if you can get maps to install via the tablet.

If it won't install even on a freshly reflashed tablet then there's probably something physically wrong with the tablet.

If you need help with reflashing the tablet, check out this tutorial:

http://tabletschool.blogspot.com/200...-firmware.html

As sachin said, don't restore the backup, see if it works without restoring first.