My in-laws bought a MacBook Air in December 2020 and just opened the box yesterday. It runs off the cord but the battery isn’t charging. Would the year+ of lying dormant have killed it? If so, is there any way of bringing it back to life?
It’s possible that the battery is wrecked, but I would try an SMC reset before giving up.
Google it for the specific model.
If an SMC reset doesn’t work, or leaving it plugged in and sleeping or turned off for a day or two, an out-of-warranty battery replacement is $129, which isn’t too bad. At that point it’ll be basically a brand new machine again.
I have a Macbook Air from 2011. After leaving it sit for a year or more uncharged, the body swelled up badly. For $50 or so, I bought a replacement battery and tools on-line to replace it. (It was too old, Apple would not touch it.) When I got the battery out, a few of the soft-battery sacks were quite enlarged.
If the keyboard is not bulging, your battery is not too badly damaged - yet. If it is a fairly recent version, Apple will replace the battery. At the same time I presume they will tell you if the problem is the battery or the charger, or the motherboard. Odds are it is the battery - a simple repair (replacement).
I don’t think swelling is as much of a concern for a new battery. It can die and still maintain its shape.