Remove the battery.

Don't reinstall a damaged or deformed battery, as doing so is a potential safety hazard.

If you're reusing your old battery during reassembly, you can reuse the existing adhesive to secure the battery during reassembly.

Alternatively, remove the old adhesive with high concentration isopropyl alcohol and a lint free cloth and use a small piece of double-sided tape such as Tesa 61395, or a dab of liquid adhesive such as E6000.