Just to hopefully help anyone else going down this rabbit hole like I did... I had the same problem – I left the pencil (2nd gen) uncharged for several months and when snapping it to my iPad, it would register the pencil, but say 0%.
I tried everything I could find in every thread on the issue – reseting the bluetooth connection, hard resetting the iPad, etc. Nothing worked.
I read that the small battery in the pencil completely dies beyond recovery when leaving it uncharged for too long. I was feeling mucho dismay and planning a burial of my once-neglected pencil.
And yet WAIT, that once-dead pencil is now working... I'm honestly not sure what did the trick, but the only thing I did between it once staying 0% and it suddenly resurrecting from the deathly graves is the following:
- I released then snapped it back to my iPad several times over and over for a couple minutes.
- I then left it snapped onto my iPad with my iPad plugged into a charger overnight
- The next morning I repeated the snap on and off procedure for a couple more minutes.
- I came back to it some time later in the day and it had risen from the dead and worked perfectly