Sorry, but why should he have to explain why he needs help? And what if he is now out of warranty?

 

I checked it out for you. If you look directly at the bottom of the moving dash piece, there is a section that can be pulled out.
It is held in by two clips. Pull that firmly from the part closest to the front of the car.


It'll pop off and expose two screws. That is where you should start.

 

sounds like he got his lease miles reversed just under the a loted mileage, and when they removed the '1time use only' needles they tried to put them back and it didnt workout for them LOL-happens all the time with certain speedo's.
some cars track mileage in the headlight module and or suspension modules(dodges) some also in the key(mercedes) and some in such random places, that modding just the speedo isnt enough.

PS: im not sure you would have to remove the whole dashboard for this process, as i have not messed around with a g37 dash.
but look at the speedo, on the top shroud should be 2 screws... try and also take off any molding around the speedo. most of the time its only held on my 2 or 4 screws. the wiring harness on the back is a wide plug, and it clicks in & out. speedo's are not 'hard wired'.