Before attempting to dissemble the kettle to remove the lid, I'd suggest that you try to descale the latch mechanism in the lid to see if that helps.
Using a descaling product or if not available, vinegar works as an alternative. You will have to figure out a way of soaking just the lid in whatever descaling liquid you choose to use, probably by balancing the empty kettle upside down with the lid open and just the lid submersed in a small bowl of the liquid for an hour or so. Remember to rinse well in running water and allow to dry out before powering up.
Rupert, March 2020
