I took the pads out because they were rubbing and the pistons were too protruded to fit them back in without rubbing. I pumped the brake thinking they'd retract when I let go (realised straight after what I'd done when the pedal went hard) then I undid the caliper (didn't remove any lines or nipples) and after removing the bottom right bolt, fluid exuded from the caliper and now the fluid level is below min. I reattached the caliper after pushing the pistons back in slowly using a clamp, then I put everything back as it was but when I drove the car forward on the drive, pushing the pedal did nothing, it was very soft. I could hear some sort of air or gas when I press it but no bite...