Power off the device by either pressing and holding the power button located on the back of the device, or unplugging from power and removing the battery.
Remove the plastic cover found on the bottom of the modem.
Remove the battery.
Remove the old SIM card and replace with the provided replacement, in the same orientation.
Power your modem up and give it about 60 seconds to power up.
If service is not restored, conduct a factory reset on your device by holding down the reset button for 20 seconds
Follow the device setup instructions found here