My 2004 Impala Trunk Won't open, why?

Tuesday, on my way to work it was raining a little, so when I got to work, I opened up my trunk and took out my umbrella. I had an appointment to get my brakes worked on later that day at the Raben across the street. On my break I dropped it off and walked back blah blah useless info. I get the car back, everything seems fine. Brakes are better, I'm happy. Until today. I needed to put something in my trunk, and when I hit the button on my remote, and I heard a whir, but nothing happened. I tried a button on the insde, same noise, no dice. I tried the key, and it wouldn't budge.I tried pushing down on the lid and various other tricks with no dice. My trunk is not very full so I doubt something is in the way, and there are no visible signs of damage where something hit me and perhaps put anything out of line. If memory serves me correctly, I remember hearingsometimes cars fall of the lifts at mechanics, and while it may land on its tires safely, it can do all sorts of crazy damage. So, in your expert opinion, was this in all likelyhood caused at the mechanic? Should I make them fix it, in light of the fact they might screw me again? Can I fix it on my own? If it was really dropped, what else might I want to check for damage?