Has my washing machine killed my precious?

My 120GB iPod classic 6th gen decided to go for a joyride in my washer. Of course, I discovered it was still in my pants pocket after I heard it clunking in the dryer. I immediately took it out and put it in a bag of rice for about a week. It no longer turns on unless plugged in. The moisture indicator inside the headphone jack has not been triggered. I opened it up to look around inside, and there seems to be no visible water damage. I was able to access the diagnostic menu, and it passed all the diagnostic tests. It just doesn't hold a charge. The hard drive still spins, and the screen works, as long as it's plugged into the wall. Is it possible that it just needs a new battery?