Your local place does not know what they are talking about. For a pre-July unit to do the flash the headlights trick, you DO NOT ground the parking brake. Having the parking brake grounded usually interferes with the flash the light bypass and will eventually stop you from doing it all together.
You want to UN-GROUND the parking brake wire and then reset the unit with the recessed button to the right of the eject button. Then the parking brake warning will never come back and if you flash your lights every time you will have a fully unlocked unit. The circuit I make and sell basically does the same thing, it will tell the Z1 that you flashed the headlights, that's all... just so you don't have to do it. Having the parking brake grounded will interfere with my circuit as well (because as far as the Z1 is concerned, there is no difference between my circuit installed and you manually flashing your lights every time you start the car). My circuit just "does it" for you so you don't have to (and my circuit won't actually flash the lights either).
Do that and you will be good to go.
Or you can update the Z1's bluetooth interface software and it updates your Z1 to the new bypass, but a couple people had that disk fail and leave their Z1's unusable till they (me and one other guy as far as I know) restore the hard drive from a previous backup we made of it. So update at your own risk.
There is no bypass for the 2 disclaimer screens (the nav and dvd in motion). Sorry.