Canon AS 6 - Manual (Page 53)

Do not touch the shutter button O while
rewinding the film.
To rewind the film before the end has been
reached, cover the lens O with your hand
and press the shutter button repeatedly until
you reach the end. At that point the camera
will rewind the film as usual.
Since the body is sealed tightly, the back
cover may be hard to open if the air pressure
inside the camera is less than atmospheric
pressure. In this case, equalize the pressure
by removing the battery magazine ® , and
then open the back cover.
If you take more than the number of shots
specified on the roll of film, the last frame or
two may be cut off in the developing process.
When the battery power is not sufficient, the
camera doesn’t rewind the film. In this case
replace the batteries.