AP-701 - My pen is not detectable by Windows any longer. What happened and how do I fix it?

Question
My pen is not detectable by Windows any longer. What happened and how do I fix it?

Answer
We have found that in our earlier firmware versions, 2.1.x.x (and earlier), this issue could occur. This appears to occur when the pen's DOTPOS chip (the chip that generates the camera images) gets into a state where it repeatedly delivers 'empty images' at such a speed that it freezes the function of the pen.

Why does it happen?
This can happen very rarely in firmware versions 2.1.x.x (and earlier) and we believe that it is caused by an EMC (electro magnetic charge).

How do I fix it? 
In firmware version 2.1.x.x (and earlier), you'll need to totally deplete the battery of the pen (a fast way to do this is to have the pen in a constant penDown state). Once depleted, please charge the pen back up again and normal functionality will resume.

In firmware version 2.3.x.x (and later), we have addressed the issue by ensuring that the pen is still detectable by the PC when getting into this state; and it will now still be detectable by the PC when docked; subsequently, performing a 'Factory Reset' on the pen will re-establish normal functionality again.