See those little plastic pegs? Those prevent the logic board from being freed! (I think it's to maintain key rigidity and proper function. My keys worked fine after this, but they were pretty mushy.)

You're not going to like this step, as it involves prying with a screwdriver and breaking these awful pegs off! So pry until the pegs in that area break, then move down the board!

The board is free!

Also, this little epoxy blob appears to be the processor. I could probably melt it off if I desperately wanted to, but the calculator works fine. If someone does, send me pics! I'm assuming the processor is ancient Texas secret. Or just some propietary chip.