What I mean by flat is that the battery was run down to zero and the Pencil battery was left in a flat ( zero charge ) state.
If left uncharged and with the battery at a zero charge state for 3 weeks of more, the battery in that Apple Pencil is dead and you will need to get another new replacement Apple Pencil 2 from Apple or authorised Apple reseller.
It is still under one-year AppleCare warranty.
So, you should be able to just get a new, free replacement Apple Pencil 2 from Apple.
FYI and something Apple never divulges to it potential iPad Pro/Apple Pencil customers/users unless the potential customer/user is smart enough to ask about, AND still appears to be problematic with the new generation of Apple Pencil,
Due to the “always on and active/standby” nature of the Apple Pencil and, also, due to its very tiny rechargeable Li-ion battery (smaller than the eraser head on a REAL wooden pencil), the Apple Pencil needs to be constantly charged up to some significant charge level ALL THE TIME, even when not using the Pencil for prolonged periods of time.
The Apple Pencil needs to be kept charged to a minimum of 5-10% all the time.
If the Apple Pencil battery is allowed to drain down to 0% and allowed to stay in that flat, zero charge condition for more than a few weeks, or so, OR EVEN LONGER, that very tiny little Li-ion battery is too small to keep at a 0% state for a long period of time and it will fail and the Apple Pencil will be dead and you may have to “pop” for another $99 or $129 Apple Pencil, once again!
