That does mean a battery failure, not dead, but not powerful enough to keep working.
The next thing you should do is inspect for water damage. Inside the battery cover there are a couple of stickers. If they are red, you need to insure it is fully dried out before trying to restart it.
Best way to do that, put it in a sealed plastic container over with dry rice. Leave that in a warm place for at least 24 hours. The rice will draw out any remaining moisture.
Good luck, I am sure a fresh battery with get it working again, but just in case:
I saw a thread on here a while back about this exact problem. I don't know how to attatch a link to the thread so i'll type out what you need to search for in this forum:
"battery on screen with red line through it"
Not to freak you out or anything, but it involves dropping your BB!!