On those old M series cameras its best to use a coin to unscrew battery cover. 10c piece is about right size. Right hand thread so anti clockwise. If its to stuck try a drop of anti seize or Penatrol, just a tiny amount and don't spray all over. Same if its corroded. If that is still stuck you can drill 2 small holes into the cover, insert 2 small bits of stiff wire and put a screw driver between them and unscrew that way. Replacement covers are available on ebay.
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On those old M series cameras its best to use a coin to unscrew battery cover. 10c piece is about right size. Right hand thread so anti clockwise. If its to stuck try a drop of anti seize or Penatrol, just a tiny amount and don't spray all over. Same if its corroded. If that is still stuck you can drill 2 small holes into the cover, insert 2 small bits of stiff wire and put a screw driver between them and unscrew that way. Replacement covers are available on ebay.