Battery stuck?
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I just had this problem a few days ago too. My advice is to use a flathead screwdriver and wedge it under one of the terminals on the battery to get some leverage and try and lift it out from that side while pulling up with your fingers on the other side. It worked for me with some wiggling and finessing. Also, there's a small hole about the size of a quarter or so in the battery tray directly centered underneath the battery. Kind of hard to see and get to but maybe you can push up with something through the hole while pulling up on battery at the same time. Hope that helps.
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