How do I reinstall from scratch to my TomTom XXL?

SOURCE: iT is a xxl 530 s tomtom. Do you keep the unit

While in drive view, tap the screen on the blue status bar, on the GPS signal strength. A new screen appears showing the battery charge level at the top right corner.

SOURCE: i have a tomtom xxl

First you need to reset the tom tom by holding down the power button for about 10 seconds, it will restart itself, from there it should get passed the tom tom logo.
If it does not do the job, then you need to connect your gps to a computer, then back up the files then you restore the files back on it after formating the gps.