APS is as you correctly say, ie the initial settings automatically loaded onto the TV when new and you turn it on for the first time.
We had horrific high winds overnight and that took out the Sky box, etc. I was trying to set the TV to terrestrial TV and ended up with 'no signal' being displayed. I tried what I thought was the APS but all it did was delete all the programme settings.
Your instructions looked vaguely familiar and indeed they were as this was exactly the procedure that got me into this mess in the first place. Needless to say, this has not worked. Any other ideas?