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drill access hole in rotor at the proper position to get at the adjuster?

You might look at the emergency brake cable adjuster (if there is one) to see if it allows any release of the e brakes. Might be different than on the MB.

This isn't any big deal to solve and the dealer won't be doing anything different than a regular shop will.

Pull the rotor against the lip and rotate the rotor as you pull. This is usually enough to get things going. It might take a few pull / turn actions to get things going. Sometimes it helps to put a pry bar across the wheel studs to help in rotation.

If this does not work, locate the parking cable adjuster and slacken the cable, ( or even disconnect and feed cable back in ) This might give enough space to get things gong.

+1


Alternatively have him trade in that smelly old chic repellant.