2006 Chevy Trailblazer Battery and Healights

I recently had the Ignition switch changed on my car and now the battery light stays on when the car is turned off. And if I leave it off for too long it will kill the battery so I am having to undo the battery cable everytime I am going to leave the car off for more than an hour or so.. I tested the battery and the alternator neither are bad .. Now after doing this for a few weeks my low beam head lights don't want to work and they are not burnt out I had them checked. I don't know if it is because of the battery problem or because of the ignition switch being installed improperly.