Do you meant yours is in lambskin? Or distressed, cuz matt definitely sounds like lambskin. My coffer has been with me since 2007 and its still as good as new, i did not treat it with anything at all and its very soft and leather still perfect.
Regarding ur 'lock' accident, I did try to lock mine before and it seems you need to do a double turn to unlock it. As i was ever stuck before and i cant open it, but i slowly turn the key twice (cant recall anti clockwise or what) and it open. So mayb you like to give it a try. GL!