Imagine if you will, having a deadline where you have to finish a voiceover project in the next half hour or so. Part of the setup for your Macbook Pro is the bluetooth trackpad and keyboard.
I only use those items when I record, and I don't necessarily record every day. The reason I use them is so I can isolate the CPU fan in another room, leaving a nice, quiet work space in front of the microphone.
I turn on the keyboard, the icon on the screen shows me that it's engaged. I turn on the trackpad, no icon.
I opened the cap on the upper right end of the trackpad to see if a new battery might help.
This is what I found (left), only facing down, and not until I devoted about 20 minutes to attempting to extract it and its twin.
How do you remove a swollen battery from its enclosure when it's surrounded by corrosion and lodged tightly in its aluminum housing? Well, prying it loose doesn't work, so you have to bang it against something. It's only $69 after all, and if I break it, I can go to the Apple store and buy another one... for $69. And the Apple store is 15/20 minutes away. The whole trip should take an hour after parking, waiting in the checkout line, traffic. I'm still trying to finish my voiceover recording in half an hour. Time to start banging.
First few whacks: no movement. Do it again. Nothing. I know! I'll use some contact cleaner, some DeOxit spray right into the tube. What have I got to lose? It already doesn't work, and I might be able to fix it after all.