I’m uncertain that a lawyer would help in this situation. The dealer (nor Infiniti) has no legal obligation for your QX60…the fact that the vehicle won’t fit in the garage has no bearing on anything.
Have you tried negotiating any type of return/exchange with the dealer? I would begin by begging them to help you out. I think this is going to be ugly, regardless of how you cut it. The other option to consider - how much is convenience worth to you? Yes, it sucks to be unable to use the garage…but I personally wouldn’t dump thousands of dollars (in a matter of days) just to get my parking spot back.
Worst comes to worse. Go to ever personal lender in town and take a high interest loan for 1 month (and declare it to your dealer) when they try to fund your Infiniti. Blow your own DTI through the roof. When funding fails, return the car, unwind the deal and return the personal loans.
Your only expense should be 20% interest for one month. Haha.
If OP is still in the market for a car, the dealer wouldn’t possibly be willing to help with unwinding this if they were willing to sign a new deal for a smaller Infiniti on the lot?