Burn smell

As described, your description suggests that your iPad battery has a fault or has been seriously damaged. Do not attempt to charge your iPad under any circumstances.

As a precaution, until you are able to take your iPad to the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP), place your iPad someplace cool and dry - away from any flammable materials.

Genius Bar Reservation and Apple Support Options - Apple

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We want to make sure you reach the right team for help with your device. We recommend that you contact Apple Support directly. Depending on your region, you may be able to reach them here: Get Support.

I would turn off the iPad and take it to the nearest apple store. (Apple Store - Find a Store - Apple)

Your iPad's internal battery could be dangerous so I would take to a apple store.