You said the whine / static and all that was gone, now the only problem is the premium sound not working
As has been said, most of us don't know about stock audio systems, but. The dynamic sound button I'm assuming is like the built in audio boosts on aftermarket headunits. Mine is a Stereo MX button that adds 35w across 4 channels. If your button does nothing, (without me seeing in person) i'd guess either an option was changed in the headunit or there is a fault in the headunit.
Try testing the premium sound with all methods of input you have (cd, tape, radio, ipod). If none work, try and find a friend or a dealer that will let you swap headunits to test in your car, see if yours is faulty.
Also look into the settings on it. Tint guys could have been jammin' while doing the install and hit a button or ten.
And to answer the question about the premium sound amp being blown, it wouldn't make sense to me to have two amps in a circuit that your button switches between. The sound wouldn't work at all if it was routing through a bad amp. I'd say it's just one amp that, when you press the button, it draws more power.
Anyways. Hope you get it worked out.