17802393 Tailgate Lock Package - Codeable Wil No Longer Work

[Scoobydoo1]

I decided to place a 17802393 Tailgate Lock Package - Codeable into my 2007 GMC.....it was working great mind you i only used it a couple of times in the last month as i haven't really put anything into the back tail gate. Today I go to put the key in to open the tail gate and it would not turn in any direction. I have a hard tunnel cover and can't get into the back... I tried wiggling the key but it didn't work....the tail gate lock was installed by a mechanic....it's the weekend and I need to get into the tail gate, and I was just wondering what might be the problem? Can someone let me know how I might fix it myself...I know it was coded to my key cause it was working but now it won't budge at all and its only a month old.