With all due respect and not suggesting you are to blame, but LBSs see broken derailleurs every day and 90% of the time it's caused by the user.
There is a process to warrantee and every shop will handle it differently. Hopefully, your shop will find time to do it expeditiously.
If I could judge with little doubt the problem to be a part failure, then I'd likely just swap it out from stock and deal with the rep for replacement later. If it was obvious the thing had been crashed or otherwise misused, most times I'd be upfront and tell the customer, sorry warrantee won't cover this, rather than passing it off to the manufacturer to rule on.
However, if a customer gets stroppy in such a situation, then I'll fall back on the manufacturer's arbitration.
