did you ground the battery properly ?. did you hook the original ground to an extended wire to go to the battery ? or did you ground the original ground to the engine bay ?. if you dont have a good ground, it wont power the car enough to turn it over but enough to get power to the relay's. a picture of a wiring problem is very valuable cause we could see whats happening, where your wires are going. Did you check your ecu fuse ? you should be using a larger diamater wire being you located the battery further away from the places its needed, its possibly losing voltage cause of the extra distance. did you accidentally put those two black wires that go to the boxes on backward ?. please tell me you ground the battery seperately if you didnt extend the original ground. ? you just need to double check things, swapping a battery to the back is a very simple procedure.