That’s impossible for me. As much force as two hands on the tool still won’t crack that seal…looking at that picture with a thumb and finger’s amount of pressure makes me think that you are Superman.
No trick, follow instruction in reverse substituting the new battery and you’ll be golden.
This image shows at best an aspirational use for this tool. I have used so many of these and they are mostly useless except for prying up the connectors. As soon as you get about 1mm into the case it shreds and loses the edge, or breaks right below the reinforcing part. Tell me I’m wrong.