Here is some information not readily available for the Dash...
To perform a hard reset (Erase ALL your data) on the t-mobile dash hold the two soft buttons down then while holding those buttons hold the power button for 2 seconds you will get a prompt to press 0 to reset. Time is of the essence if you miss it try again.
Edit: Here is a second easier method:
If you cant get this to work you can navigate through these steps as well:
Dash Hard Reset
1. Select Start
2. Accessories
3. Clear Storage
4. Type 1234 in the box
5. Select YES.
