Join Date: Mar 2019
Location: Near Helsinki, Finland
There are different reasons why the seat lock wont operate. If it's only the lock that is broken or the nut on the lock has come loose, try this: take a piece of steel wire, bend one end about 1 cm in a sharp angle, try too hook the cable near the key hole and pull.
With the same piece of wire, you can try to hook the latch from behind the seat.
I'll try to post pictures later today, when I've been to my garage.