Overlander

I had a brake tube leak, its now been repaired. Most of the brake fluid had leaked out of the braking system. I refilled the brake fluid reservoir and in sequence starting from the wheel at the furthest pointfrom the reservoir tried to bleed the system. Ive tried to do this a few times, I get fluid at the nipples but the brake peddle remains completley spongey and the brakes are absolutley ineffective. I would be grateful for advice.