No very small reset button available ?
I'm most worried about you don't see it within TomTom Home.
When it's running out of power did you connect it with your computer and switched it on ?
Normaly Home will start when you set it in the program.
Otherwise start first Home, than connect and start the device.
If there is no USB communication, the Bootloader which is in a e-eprom must be faulty.
Anyway, read next excellent manual:
TUTORIAL: Clean Install - How to install the latest map and navcore from scratch!