Hi guys I just recently got a z2 and after installing it last night the screen goes no further then "starting pioneer navigation". I was wondering if anyone has any clue to what i might be doing wrong. I'm installing it in my 04 altima and all the wires seem to be straight forward. The only thing that is not installed and I don't have is the gps thing, so I don't know if that has anything to do with it, if so is there a bypass mod. I'm only using as a normal stereo no amps subs etc.

Sounds like a software or hard drive issue. It could also be the z2 firmware "freeze". Try power cycling it a few times to see if it will start. Your wiring can not cause this to happen. You can completely boot the unit by only connecting yellow, red, and black...

I actually have no idea if it will start up without a GPS antenna connected ... Don't you have one to (temporarily) connect, to see if that solves the problem ?

Yes, it will completely boot without the GPS antenna connected. You only have to connect YELLOW (+12v), RED (+12V), and BLACK (-12V ground).