If your bike is still under warranty, take it back to the shop and get them to deal with it. Don't go wrenching a bike that's still covered - it's a waste of money and time that may end up costing you big-time.

I've found that many sharp clicking noises coming from a crank are due to the cartridge bottom bracket moving very very slightly inside the BB shell of the frame. I've found that anti-seize compound (not grease) smeared onto the threads before installation solves it. I know others and some manufacturers use thread-locking compounds.