The adhesive that holds down the battery in the Huawei Mate 20 is extremely strong. In most cases you'll need a combination of high isopropyl alcohol (>90%) and heat to remove it.

Try your best not to deform the battery during the following removal process. Soft-shell lithium-ion batteries can leak dangerous chemicals, catch fire, or even explode if damaged. Do not use excessive force or pry at the battery with metal tools.

Apply adhesive remover or high isopropyl alcohol (>90%) in every corner of the battery and let it penetrate the adhesive beneath the battery for several minutes.

At this point you can attempt to continue with the following steps. If you aren't able to pry up the battery apply a heated iOpener to the screen to loosen the adhesive beneath. Apply the iOpener for at least two minutes. You may need to repeat the adhesive remover and heat procedure several times during the removal procedure.