I have a Sony BP-U30 battery that came with my PMW-EX1 a few years ago, and I'm pretty sure its dead. All four of the battery indicator lights blink in sync with each other, and the charger status light blinks between green and orange rapidly.
Is this the normal behavior when it no longer takes a charge?
I had one that did that this last summer. I can't say that it is normal, but it did die. I emailed Sony and sent it to a service center. The only thing I got from them was a confirmation it was dead and the replacement cost of a new battery. No one could tell me if it was normal.
I was a bit surprised of how fast it happened, which was why I wanted it checked out. It went from normal to nothing overnight and I was worried that the charger or camera might have caused it. But my other three batteries have been working fine since.