Arris M900 - Radio Password and Safety Switch; Setting Return to Home Height

matching to rebind it again.
5. What is the password for the radio?
The password is “999”.
6. Error “Pre-arm: Hardware safety switch”
This means you did not turn on the safety switch on the GPS. Long press it will turn
on it.
7. How to set the flight height of the drone for return?
Enter Menu--”General Settings”-”RTL--ALT”--Input the height--Save.