Will Dell cover battery for my warranty?

When my alienware 15 r2 was running it suddenly shut down, when i turned it back on it said "Your battery has experianced a permanant failure". I restarted my computer and went to BIOS and under Battery Health it said the same thing. I believe that the only solution is to get the battery replaced, and i want to know if dell is going to replace the battery as im still under warranty. Also, what are the causes of permanant battery failure? I don't see the battery under my laptop so i'd have to open the laptop to get to the battery.