This was on my 1940 Ford Tudor Sedan. Everything was new, latch, license plate bevel and handle. Closed the trunk. Wouldn't open. Handle would only turn 30 degrees.
Gently lifted the lower corner of the passenger side trunk lid. Pushed the gasket inside. Duct taped a 12 point 9/16 box wrench to a 1/2 in by 1/8 inch 30 inch long bar. Slid the wrench through the gap created by the gasket removal. Put the wrench on the nut holding the handle. Turning the handle 30 degrees is just the right amount to turn the nut through one twelve point notch in the wrench. Once loosened, you can spin the nut off. Remove the handle. You then have access to the square hole to turn the keeper using a screw driver. In my case I was able to access the top of the locking bar on the right hand side. There is a right angle bend. I put a wire through it and pulled it up. Trunk open.
Note the new handle and bezel combination did not allow enough rotation to unlock the trunk. I had to grind off both the handle and one stop in the bezel to get enough rotation. Lesson learned, make sure you can move the latch tab all the way into the trunk lid before closing the trunk!