for the way my box is setup, this maybe different to yours
menu
Setup (5)
video (1)
basic settings (1)
down to mode (down arrow twice)
mode (left arrow once for 720p)
or to change video out put to scart
menu
Setup (5)
video (1)
basic settings (1)
left or right arrow once
can you not get to in by computer, tablet or phone
type your ip in to the address bar? if you know the ip address