Pull the power cord and re-plug it.
When the phone says “booting” hold the 1 and the 9 keys and keep holding until the phone says Factory Reset and asks for the admin password.
To enter the password, you will need to press a key multiple times to get the character you want, such as “ABC1abc” you would press 1 several times to get to get to the small ‘b’.
Press the large DOT key in the middle of the arrow keys.
Phone should reboot and re-program itself.