Your rear pads seized onto the rotors. Further, likely the brake pistons seized a bit. Have you inspected the pads? Have you removed the calipers to inspect the pistons and seals?
Next season leave off the emergency brake then at the beginning of the new season jack up the rear a bit and hand spin/rotate the rear wheels to ensure they're not stuck.
Replacing the seals isn't extraordinarily complex... and rebuild kits aren't terribly expensive.
That's what I'd do.
Good luck!!
