I have a 10th-generation iPad and bought what was sold as a new first-generation Apple Pencil. The iPad and Pencil are definitely the correct models, and I've used another first-generation Pencil with this iPad before. This particular Pencil won't connect at all, even after restarting the iPad. Could the battery be dead, or is there a special way to pair it?
3 Answers
Make sure the iPad is updated, remove any old Apple Pencil entry from Bluetooth settings, restart the iPad, and then connect the Pencil through the adapter. A Bluetooth utility app may help confirm whether the Pencil is broadcasting, but it won’t revive a failed battery. If the Pencil was bought from an unreliable seller, counterfeit or defective stock is also possible.
Even if it was sold as new, a first-generation Pencil may have been sitting in storage for years. Its small internal battery can fail completely after being discharged for too long. Try charging it with the proper adapter for a while, then check Bluetooth and attempt pairing again. If it never appears or charges, return or exchange it.
A first-generation Pencil has to pair through a Lightning connection. With a 10th-generation iPad, you need the USB-C to Apple Pencil adapter, plus a USB-C cable, to connect the Pencil for pairing and charging. Simply plugging it into the iPad without that adapter won’t work.

That’s probably what happened with mine. It looked unused, but it wouldn’t charge at all, so exchanging it was the only practical fix.