Yes, different microwaves have different power levels (e.g., wattage) so one microwave may explode the iOpener after 31 seconds of heating whereas another microwave will barely warm it. It would be helpful to have a more precise target temperature. My microwave is fairly weak so I’m heating it for seven seconds for every two minutes against the phone. In theory, this should slowly add more heat than is dissipated into the phone and surrounding atmosphere.