Most Macbooks are going to show symptoms before catching fire -- which is thankfully a very rare event. For most people, it's going to manifest as a swollen bottom case. Here's what I look for:
- If you put your Macbook on a flat desk, does the aluminum on the bottom touch the desk? (The rubber feet should touch the desk; aluminum should not.)
- If you close the lid, does it seal all the way around? (You shouldn't need to apply pressure to make the lid seal. Closing the lid should not bend it. It should not pop open on its own.)
- Cracked trackpad is a bad sign
- Look along the edges; any warping is a bad sign too
I had a swollen battery that manifested with a trackpad that couldn’t click but I thought it was maybe damaged from accidentally dropping something on it that I couldn’t remember. Had it like that for many months until I googled it. Replacing the battery fixed it straight away.
https://www.reddit.com/r/apple/comments/bulbhv/my_macbook_pr...
Relevant HN thread: https://news.ycombinator.com/item?id=20240359