1. Sometimes when a battery has taken a deep discharge the battery will need to be charged for a period of time before the device will power on.
2. Place the device on charge through a Cat power adaptor and USB to AC supply. Leave the device to charge for 45 minutes and attempt to power on.
3. If the device still does not power on, remove the battery and re-seat in the battery bay and recharge.
4. If the device still does not power on, check that the USB cable is not damaged, then recharge.