When your device is not working properly, you can do factory reset to recover your device.
Factory reset will erase all data from your device's internal storage, so backup important user data before doing factory reset.
PM451
Navigate to Settings > System > Advanced > Reset options
Tap Erase all data (factory reset)
After being aware that factory reset will erase all data from the internal storage, Tap RESET PHONE
Tap ERASE EVERYTHING to start the factory reset process
Press and hold SOFT_RIGHT and Fn in the sequence of keys when PM451 is turned off
(If the device is blocked while booting, press the power button more than 7 seconds to force to restart, and then press the above key sequence)
Refer to below image to figure out the key sequence by keypad type
After short vibration, release the keys
Now your device is in Android recovery mode
Using the keys below, select Wipe data/factory reset
After wiping the data, select Reboot system now
