Not necessarily. Buttons and switches introduce contact resistance, which in the case of the mushy Duracell buttons, is relatively high and also dependent on how hard they’re pressed.

Ideally, the buttons are pressed very hard to ensure the entire contact area is closed, minimizing the contact resistance from the buttons. A good switch should have little resistance.

Poorly closing the contacts by not pressing the Duracell buttons very hard would result in higher contact resistance (because there’s physically less contact between both halves of the switch), which means less current flows through the strip and less heat is generated. This would look identical to a deader battery with the buttons pressed well.