Tampering with the stock firmware almost universally voids the manufacturer's warranty. If you damage the device during the process, the carrier or manufacturer will not replace it.
Do not reboot. Perform a power cycle while holding the reset button for 30 seconds. If still bricked, you need a serial TTL recovery and the original stock firmware from ZLT’s support site. unlock-zlt-p21.bin download
Ensure your device is compatible and that you have the necessary drivers installed on your computer. A backup of your data is also essential. Tampering with the stock firmware almost universally voids
The router will reboot. Do not touch it until the signal lights stabilize. Troubleshooting Perform a power cycle while holding the reset
The most secure way to unlock a device for use with other networks is to request an official unlock code from the original service provider once the contract terms have been met.