Check the pipes going down to that caliper. One might be bashed or something. Also trace it back and unscrew it at the abs pump and see if it blocked or dry there. Also get an easy out and remove the bleed nipple and replace it. Bleeding from the banjo will leave you with a spongy pedal. Also pumping the pedal with the banjo bolt loose is unlikely to bleed the system anyway as every time you lift the pedal off it will just draw the air back in. Theoretically you should have started from the N/S/R. Try all those and let me know how you get on and we will go from there.