MacBook Pro 2012 - The old battery had done what old batteries sometimes do, alarming my stepdaughter and pushing the trackpad out of place.
The hardest part was easing the case screws out without damaging the heads or the case but was able to do it after a lot of gentle easing and pressure on the iFixit screwdriver I had from my old job (Apple repair tech for 22 years...). Case off, old swollen battery out; reseat the trackpad; install new battery, done. Everybody happy.
Patience is key; the screws will come out with enough gentle encouragement. Or the case holes will give way, that works too