Is the tumbler portion of the lock completely removed? In other words, can you stick a finger inside? If not, that should be your focus, get the tumbler completely out so you can see inside. Drill it out with a slightly bigger drill bit if necessary. Be careful not to force a drill bit deep inside, you can drill through other stuff. Put a spacer or something to prevent it from slamming into the machine.
Once you get the tumbler portion of the lock out you can usually get a finger inside enough to push the door latch unit up and open open the door. The lock on most machines (I'm not completely familiar with your model) is a bar that goes from the bottom of the door to the top and drops onto latches in two or three places. That bar slides up and down when you turn the key....if the tumbler is removed you can replicate that action with your finger. You might need to use your little finger or borrow a smaller person.
In general, you will have difficult time taking the wood case apart, these machines are designed not to be easily penetrable. You might have to break glass. Having said that, I haven't run into a situation where I couldn't move the locking mechanism with my finger. I typically work on older machines though.
If someone is more familiar with your specific machine they will jump in and clarify more.
Last minute modification: I re-read and saw you said the lock was set so you can turn with a screwdriver. Try lifting the door a little and turn the lock with a screwdriver, it might relieve some of the load. If the tumbler is drilled out and the lock turns with a screwdriver that should work.
Best of luck.
Chris