Try any older 240 trunk key,try rocking it up and down(6and12)while sliding in and out and turning,I have used this method on many 240s with great success or 10mm socket on long extension through ski hole works pretty well.
good luck

Not sure if it is the same as on the earlier cars but on the earlier models you can drill
the lock out, starting with about a ¼" drill and go to increasingly bigger sizes.
By the time you get to about 3/4" you should have enough of the lock gone that you can
work the trigger that does the unlatching.
This would work on a 140/164 - might on later models. Worth a try.
--
George Downs, Bartlesville, Heart of the USA!

if you're in the mood for crawling around....

Look for a hidden magnetic key box under the car.. never know.

Maybe, like me, you'll find a dozen or so sledge hammers in there.. oh to find a dozen sledge hammers in the trunk of a parts car.. fun fun fun.

--
-Matt I ♥ my ♂

I recall this question before and the response was to use many extensions to reach bolts from the ski hole in the back seat. I think someone also mentioned reaching through the taillights openings.

Does the central locking work? I think if you pull the driver's knob up from the inside the locking system will unlock everything.

Okay, this is brutal. Is the trunk of the car worth saving? If not, I see a 3 ft. long crowbar in your future or a drill motor and drill bits to drill out the lock. Other than that, as already stated, you may be able to access the bolts for the hinges from inside the car with the back seat removed.

The only access is through the back seat. However, you will not be able to crawl into the trunk because of the cross bracing behind the seat back. You may be able to unbolt the hinges.