press the battery check button, see if the green light comes on in the frame counter window. If the battery well cover is not screw in precisely right, you won't get a circuit. in my experience, if the cover is not level, you can still screw it in, but not get a circuit.
Pocket users: XA2, Retina IIa, 35RC
Favorite user: Kiev 4am with Jupiter 12 or Helios 103
Closet sitters that don't get out much since I discovered RF: EOS stuff.