Basic blender went bad (motor ran but spindle wasn’t rotating). I wanted to disassemble to see if it could be repaired. Three of the four screws were Phillips head. I had to cut the casing open in order to discover why I couldn’t unscrew the fourth. It was a slotted spanner.
My library has a lendable “Ultimate Screwdriver Kit” that has every bit size and type I’ve ever heard of, security Torx, pentalobe, oval, gamebit, spanner, etc etc. Also a bunch of different styles of bit holder, and a bunch of attachments like angle adapters, depth setters, torque limiters, etc. Only tangentially relevant I guess… but if you run into a problem like this again, check your local library to potentially avoid having to buy obscure bits online!