Well, with a little brute force & ignorance I managed to solve the problem!
While I'm not all that small I'm just too stupid to give up,.... :wink: I downloaded a Corolla service manual to see how the seats were attached.
I found by following the rear seat belt down there was a small bolt that held the corners of each seat in place. By removing that bolt and prying the seat forwards I was able to create a small gap bewteen the seat and plastic side panel and cram my hand and forearm into the trunk.
With that accomplished I tried to feel around for the aircraft cable that releases the safety latch on the seat (hoping it wasn't the speaker wire at the same time,....

...) Giving that a sharp tug the seat-lock released and I was able to then empty my trunk, pop the lid from the inside, and replace the friggin' lock cylinder that caused me all this grief in the first place!!!