Nissan Repair Questions? Ask a Mechanic for Answers ASAP
I would say whatever you have done has put the vehicle into a security shutdown mode, since the addded system would have attempted a start scenario without a key present.
I would recommend taking it to Nissan.
You may have already damaged the body control module.
That is difficult to say as with not knowing what you have exactly done.
Nissan is still the best way.
Other sparkies won't have the resources if circuit diagrams or parts are necessary.
Jobs like this are best left to a professional.
Sorry for bad news this time.
Do you need any further help?
I hope my advice has been of assistance to you.