Before you install a new battery:

Remove all adhesive residue from the iPad frame. Use isopropyl alcohol and a spudger to scrape off any adhesive chunks. Wipe away the adhesive residue with a lint-free cloth.

If there's any alcohol solution remaining in the iPad, carefully wipe it off or allow it to air dry.

Be sure that the iPad frame surface is completely clean and free of debris. An uneven surface can press into the replacement battery, resulting in premature battery failure.