I've read dozens of methods of restoring one but NONE have used boiling water. In fact, boiling water is a sign that you have big problems inside the battery.
There are numerous web pages telling of tricks to do it. I'd go with those from professional battery companies and ignore the DIY home brew methods.

“In a time of deceit telling the truth is a revolutionary act.”
― George Orwell

It's not over when you lose. It's over when you quit.