What type of pin was it? If it is a pin of a regular size, some do blink, and as far as I know, have non replaceable batteries. Although someone diligient and handy may be able to do it. But they are not generally made to have batteries replaced.
The big honkin' thick pins that blink and interact within the parks come with batteries, and obviously are made to be replaced.
Hate to say it. They probably are old ones that were sold cheap because the batteries were dead. Can't say for sure without knowing the exact pins.
I am a Fantasmic pin collector too. I probably have the same pin.
Good luck.