Oddly enough, I've found the opposite has worked for me on occasion. ie. a MacBook charger has come back to life after sticking it in the freezer for a couple of hours.
Time can also be a great healer. I've also found that, sometimes, one which was dead last time I tried it will be working again, if I stumble across it a few weeks or months later and plug it in again.
Although I've never seen anything like this mentioned in the tear-downs on MacBook chargers that I've seen online [eg. [0]] I suspect that there is some kind of safety cut-out mechanism in them which can sometimes get triggered and then reset itself after a while [or after some other collection of voodoo circumstances comes into alignment].
I also have some broken MacBook chargers which have thus far never risen from the dead again. So, when one does stop working, it appears to be a bit of a lottery as to whether it has actually "joined the choir invisible" or is just "pining for the fjords"
[0] http://www.righto.com/2015/11/macbook-charger-teardown-surpr...
