1994 940 Sedan.
Just bought this car, mostly for my daughter to drive but have been enjoying it myself.

Anyway, a couple of weeks earlier, I was experimenting with the trunk lock (I don't have a manual that explains anything. I am still trying to figure out what all the switches inside mean) and I used the key to turn the trunk lock to a horizontal position. The next time I tried to get into the trunk I could not return the lock to the vertical position. Naturally, this finds me in the position where I am locked out of the trunk. Locksmiths flat out refuse to look this over so it looks as if a trip to the dealer may be in store.

Before I do that, is there anything I'm overlooking? It just seems odd that the lock can go from perfect to non-functional on its own with no warning signs.

I have seen this before.
But there is no easy way to get it open.
Either you will need a lot of patiance or you will spend quit a bit to get it open.
You would have to go through the ski door in the back seat and use a long rod to remove the trunk panel.Then use a bunch of extensions to remove either the trunk latch or remove the tailight to work on opening the trunk.

Thanks for the tip. I was afraid it would be something like that.

My next question is that at this point, wouldn't it be a lot easier and cheaper to just have someone drill the lock out and then go about replacing it?

That might not work most of the time it is the latch that goes bad.You can have someone try it.You won't know for sure which one it is till you get to all the parts.

I have done it a couple of times before it takes time and patiance.

I am in the same predicament as the original poster here, namely my trunk is locked for good and the key will not turn in the lock at all.
Can anyone post step by step instructions for removing the latch through the ski door. I got the extenders, unscrewed four screws (torx head) holding the bottom part of the plastic trim in place but when I tug on the trim, it does not come loose. Is there more screws to remove? Should I tug harder?
Once the trim is off, what should I do?

Thanks for any info. My car is 1992 940GL sedan.