From what I can see online the post 2000 V70 has a similar but not identical handbrake set up to the pre 2000 V70 so asking in
S80 '98-'06 / S60 '00-'09 / V70 & XC70 '00-'07 General section is going to get a safer answer.
What seems to catch most people out with the 850 and pre 2000 V70 is that to adjust the handbrake shoes you need to totally slacken the handbrake cable, not just let the handbrake off, but go into the centre console and slacken off the adjuster there. Adjusting the shoes is then fairly standard with a screwdriver through the hole in the face of the drum(disc) to turn the threaded adjuster, and then readjust the handbrake cables. I spent too many weekends under mine trying to get the handbrake right but it was an easy job once I knew how.