broken parking brake and maintenance

i have a 2008 prius with about 166,400 miles on it that i recently purchased and took on a cross country road trip. the car ran great, except for an issue with the mass air flow sensor (which i ended up replacing) however when we purchased the car we got it from a private seller and we quickly realized the parking brake does not work. has anyone else had this issue, or is it just my luck that it’s happened? whenever i try to activate the brake the pedal will not stay pressed down, or give any indication that it’s been activated. what could be the possible reasons for it not engaging? also, with all the mileage i recently put on (~10,000 miles) i want to make sure the car is well serviced before i return to college, is there any special maintenance that i should have done to the car, or that yall would recommend to make sure its working well, now that its close to 170k miles? any advice would be great!