Remote start dosen't work

I just had a brand new key fob laser cut at the Dodge dealership. That day the check engine light was on , it randomly goes off every now and then but will clear itself within a few days. I told them I didn't wish them to check that because It is something that just goes on and clears itself. Sure enough the check engine light went off on its own the next day.Anyway…new fob opens doors but no auto start . I did everything possible, the owners manual said to click key from lock to on …etc . I also disconnected the neg battery cable . I honestly don't want to take this back to the dealership..I paid 258.00 for a new key that doesn't work. What can I do ??