Follow the steps in this guide to replace the display assembly in an iPad Pro 12.9", or to access other internal components for servicing.
Note that the Home Button installed in your original display assembly is paired to the iPad's logic board, and will need to be [https://www.ifixit.com/Guide/iPad+Pro+12.9-Inch+Home+Button+Replacement/95750|new_window=true|removed and transferred to the new display] to retain Touch ID functionality.
Before beginning, check to see if your replacement part has a daughterboard adhered to its back. If so, this guide will work for you. Otherwise, you will need to transfer the board from the old display to the new one. Transferring the daughterboard from the original to replacement unit will require specialty microsoldering equipment and we recommend DIY users source a new part rather than attempt the procedure.