so by saying parking brake, am guessing u have a dvd head unit rite?
hmm, well being a halfords fitter, i always know where to wire the handbrake cable for those that want to watch dvd whilst on the move OR only when stanionary and the handbrake is lifted all of which you seem to have identified now.
Anyhow, if anyone has wired up the handbrake wire anywhere else other than a ground point of some form, then chances are any other wire can have consequences to the unit itself rather than the car.
However, the unit should work or turn on without the handbrake wire being connected which then tells me that if you have wired it up constant, then your direct from battery LIVE wire is stil active but your ignition wire is not, if you use a voltmeter/multimeter to check if you are getting your LIVE feeds at the correct ends it will confirm this being the case. which in essence, IS a fuse that has blown. Have u checked both primary & secondary fuse boxes. You have one inside the car and perhaps one in the engine bay. Check both. IF it helps, just go over EVERY fuse to elliminate it being any other than stated in your handbook or any other instruction method.
I would say take it to your local halfords store where we can test your unit on our test board but we run 2 constant LIVES in the test board so it may perform as how u sed wen it it is always on. BUT, if thats the case, at least then after that diagnosis, it will elliminate it being the unit at fault but more your car!
Check ur fuses agen in both areas (if applicable) n see how u get on!
Goodluck n holler back on how u get on.
