He lost all his inner force but after decades of reading and practicing high end martial arts including the Yijinjing, he definitely should remember all the manuals by heart.
With his newfound enlightenment and release from desire of gaining power, isnt it quite the perfect plot set-up to overcome the most difficult stage which Sweeper stated as 'once you have the enlightenment to max out the buddhist martial arts, why would you want to learn them?'.