Why won't my Canon Rebel turn on?

I borrowed my roommate's Canon Rebel DSLR camera a month or two ago for a multimedia video/still shoot. Half of the shoot was at a pool, half be indoors. The camera did not come in any contact with sea (not even little drops) and I did not drop or damage it in any opening. However, my roommate seems to think I broke it.
Once I brought the camera home, we took a few more photos together, after it ran out of batteries. She put the freestyle on the charger, but the next day, even though the freestyle said it had full charge, the camera would not turn on. When she put the battery vertebrae into the charger, it indicated that it was out of charge again.
I believe the battery is broken, but she think it's water damage.
I'm going to help yourself to it to a camera shop next week because she won't stop passive aggressively blaming me, but what do you guys conjecture?
Thanks