nano battery dying....?

i could have sworn i charged my nano to full a few days ago and have not used it since then. right now i tried turning it on and i got nothing. i plugged it into my mac and as i type this the screen reads "please wait. very low battery." sigh. im pretty sure the battery is dead, though of course i havent got definite proof. i remember reading something about the lithium ion or whatever eventually running out and the only option being to have it replaced (battery or ipod, that is), so i was wondering if someone could point me in the right direction, or could just save my ipod as it is. =/