can't open tailgate or hard tonneau

Have a 06 Colorado with a hard tonneau. Seems like the latch for the tonneau is not releasing. Need some suggestions on how to get into the bed of the truck without destroying the hard cover.

I have an ARE hard tonneau on my 07 Canyon, and twice this winter, the plastic guard over the keyhole broke off in the tumbler. The first time it was locked, luckily the installer didn't install the tonneau cover properly so there was just enough room to lift it and open the tailgate. The second time it was unlocked. Both time I took it back and they replaced the lock mechanism. Mine was a warranty item. You might have to pay if yours isn't covered, but they can get it open without doing damage.