Lessons learnt:
1. You can’t let the battery on a macbook run down completely, to 0%, because then it becomes impossible to recharge it. You end up with a cross through your battery and a message saying “no batteries available”. This makes you sad.
2. The people on the mac forums, the ones saying that there is nothing you can do other than take it to an apple store and get a new battery, are not, it turns out, always correct.
3. The people at the mac support centre who second this advice are also not always correct.
4. If you refuse to believe that your battery could be utterly and totally dead, forever, and resolve to trust the person who told you to take it out and leave it in the fridge for a few hours, because lowering the temperatures of things helps “heal” them for want of a more technical word if they have crashed, then, when you put your newly cooled battery back into the macbook, it is not only working, but also fully charged!
Ha ha! No new and expensive battery for me, thank you very much!
Three cheers for the lone voice who said “put it in the fridge!”
From now on, I shall be doing this with all misbehaving equipment!