So, I know for my bike, the battery is "Snug", and by snug, I mean my wife has to hold onto the front handlebars while I give the ol' heave ho to remove the battery. The locking mechanism works by raising a metal cylinder up and down into an indent into the battery from the bottom, so there are no hooks to catch, and it's not at all related to the connection. Plus, you mention Seattle, I would suggest she makes sure the bike is at room temperature (inside and out) so if there has been any contraction of the battery encasement, it is as relaxed as possible. If this and extra elbow grease doesn't fix it, the most likely cause is the lock mechanism has failed and you will need a replacement (either lock or battery enclosure). ONE FURTHER CAUTION: If the bike exhibits any issues charging or powering the bike, then there is the slightest of chances you have a faulty battery (maybe individual cell) which is swelling/expanding, and you should discontinue using the bike and contact the manufacturer immediately. Again, the SMALLEST OF CHANCES, but it's the same advice I would give to any lithium battery powered device.