Two possibilities come to mind. One, you may have damaged one of the emergency brake cables somehow when jacking up the car. The cables leave the drive shaft tunnel and then connect to the axle via two tubes inboard of the brake back plates. I once worked on a car where the e-brake would occasionally not release and found one of the tubes smashed. This can jam the cable where it enters the back plate. You may also have a jam in the cable itself somewhere between the e-brake handle and the back plate.

The second possibility is that your e-brake(s) themselves, or their activating mechanisms, inside the rear rotor hats, have either jammed due to corrosion, or fallen to pieces in some fashion.

After first examining underneath for physical damage to the outside of the cables, I would pull the rear rotors and look for obvious problems. If everything seems in place, then have someone activate the hand brake while yo watch the brake mechanisms.

DS