2007 s80 v8 - parking brake applying/disengaging on its own

[Volvovlo]

Hi all,

Just turned my car off 20 minutes ago and DIDN'T apply the parking brake. Since then the electronic parking brake applies then immediately disengages itself about once a minute. The (p) light flashes twice on the dash and I can hear the motor running that engages the brake. I never use the parking brake for fear of failure, yet it appears to be failing on me anyway. I'm wondering what the fault may be and if it'll drain my battery? I need to get home from work later today and hope this won't be an issue. Appreciate any help you guys may have

Cheers