how did you get the cable back on ? sounds like you had it full stretch on the auto adjuster and have blown it getting it back on ??
the cable should be strapped up (white clip) for fitting then released to take up the slack automatically but you can remove a good cable and tweak em to fully reset but it is a definate skill to doing it
gets easier with practice
hold it vertical by the outer casing at the gearbox end (gaiter and pedal hook downwards)
slide the inner cable all the way in and check for approx 30mm of free play
pull gently and you will get another 150mm of free slack before you feel a bit of resistance
pull and push in and out and you will now have about 30mm of free play again
now the trick is to slide it down and jerk pull up against that lower 30mm zone when the ratchet jaws are open
when it works you will get instant resistance against the spring and hear a zip sound
now you will have to pull it up tight and hold on tight while you get someone to clip it closed with the white straps
is hard to do but easy once mastered and does great exercise for ya pecs and puts hairs on ya chest
i have a cable here spare (new one on mine) and can do it 1 pull out of 3