Magic Keyboard not working with iPad Pro

Presumably you refer to the Magic Keyboard for iPad and not the similarly named Magic Keyboard - the latter being a wireless Bluetooth keyboard principally intended for Mac computers.

Remove the iPad from the Magic Keyboard - and carefully/gently clean the smart connector contacts on both the iPad and keyboard with a soft pencil eraser (a drafting-film eraser is ideal). Ensure that the contacts on both iPad and keyboard are dirt and dust free - and all debris from the eraser have been removed - before reconnecting the two.

If you can't connect your iPad to your Magic Keyboard, Smart Keyboard, or Smart Keyboard Folio - Apple Support

Unfortunately, with repeated opening and closing of the Magic Keyboard, the flexible ribbon-cable connections that pass through the keyboard hinges can fracture. If this has occurred, the only remedy is replacement of the keyboard.

You would be best advised to visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to hands-on test and assess your iPad and Keyboard:

Genius Bar Reservation and Apple Support Options - Apple