Yesss, I got it opened.
Thanks for your help @Trophied.
I ended up using a combination of techniques. Squeezing as you explained did not pop the lid, but it did create a big enough gap to slide a small screwdriver in and push back the latch slider.
The problem was not the solenoid. It was dirt that worked it's way under the button and jammed the latch. Not much but enough to restrict movement. I disassembled it, cleaned it, put a bit of grease on the button guides (not the slider). And good as new.
Now, onto the next project.