There is not a manual release for 2001 up on any model.
VERY STUPID, VOLVO.
Try this, in the left rear trunk area is an access door.
Remove the door to expose the REM Rear Eletronic Module.
Remove the top rear fues #1. and reinstall said fues.
See if the gas door works now.
The REM can go to sleep.
Removing the fues will wake the REM up. There is an issue with
2001 only XC70 models with chassie number 000160-
047999. After the 047999 the REM should be programmed
with the latter SW. If doing the fuse reset does not unlock the
the gas door or release the lock you will need to remove the RH side
panel. Remove the RH rear access panel. Remove the forward
upper 10mm bolt. Located right behind the rear seat area.
Gently pull the complete side panel away from the glass area.
Do not remove the side panel, just pull the top out away from the glass.
This will expose a felt type panel. In the rear area, remove the plastic
clip going thru the felt into the car body. Pull the rear felt awar away
from the car body enought to expose the gas door lock motor.
Manually move the gas door motor rod towards the motor.
The gas door should open now. With the gas door open, remove the
2 25 torx screws from the gas door lock motor that go from the outside
of the car body into the gas door motor. Put the removed screws into the
lock motor. Let the lock motor hang inside the car body untill a repair is
made.
Install inside RH panel.
This way you can still gas up.
BD