I’ve seen a Youtube video (couldn’t find it when I looked just now) that describes disassembling to get to the battery for replacement. Probably any Youtube video about Zen V disassembly, and some that describe fixing the freezing problem (those that fix it by unplugging the battery for a while and then replugging), would show how to do this. (I don’t own the player, so haven’t tried this, and don’t know about replacement battery availablity.)