2nd generation Apple Pencil not charging

Has this Pencil been successfully used with this iPad before? If not, your iPad and second generation Pencil may not be compatible.

Here is Apple's definitive compatibility list for Apple Pencil and iPad:

Apple Pencil compatibility - Apple Support

As you will see, you can use Apple Pencil (2nd generation) only with these iPad models: 

• iPad mini (6th generation)
• iPad Air (4th or 5th generation)
• iPad Pro 12.9-inch (3rd, 4th, 5th or 6th generation)
• iPad Pro 11-inch (1st, 2nd, 3rd or 4th generation)

If your Pencil is compatible with your iPad, Here is one of the better troubleshooting guides for the Apple Pencil that may be helpful in working through common issues. This is applicable to all models of iPad and Apple Pencil:

https://appletoolbox.com/apple-pencil-not-working-heres-our-troubleshooting-guide/

If the Pencil and iPad are compatible, and you have checked through potential issues using the linked troubleshooting guide, then your Apple Pencil may be displaying symptoms of a dead battery - that will not accept or hold any charge.

The tiny internal Li-ion battery is susceptible to permanent/irreversible damage through being left discharged for long periods. Even some “new” pencils can exhibit signs of failure out-of-the-box if they are “old stock”. It is essential that if you have an Apple Pencil that you charge it regularly - whether used or not - so as to protect the battery from deep-discharge. Do not allow a pencil to remain in low-charge state for any period of time - as the internal battery will fail, rendering the Pencil useless.

If the Pencil Battery has failed, the only remedy is to replace the Pencil. If purchased directly from Apple, if the battery has failed and your pencil is within its one-year warranty, you should look to having it replaced at an Apple Store.

Gentle warming of the Pencil (such as placing on a hot water radiator), prior to attempting charging of the Pencil, can sometimes resurrect a dead Pencil battery.