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If it is like my 82. You have to reach inside the door and unsnap a flap of
plastic that holds it around the lock cylinder. The lock cylinder is made
with a metal tab that engages the door switch. The door switch is closed
around the lock cylinder and a flap snaps on to hold it. Since both the
door button and the keyswitch aren't working you need to check at the
relays to find out what is going on. You need a test light.

There are two relays in the dash one for unlock and one for lock. The
door switch depending on which way you move it sends a momentary voltage
to the relays. I've had the keyswitch on the drivers door snap a plastic
tab off and stick in the lock position. This made it so it was always
running and trying to lock the doors. But to figure that out I had to
start at the relays so you can see what signals are going to them.
I'm not that familiar with the 700s but I highly recommend spending
the $25 on the Volvo wiring diagram green book for your car. It will
help you many times worth it's price.
Dave 82 242ti