userinva, many times, there is no damage to the BB itself even when the water damage damage indicator turns red. Like many have posted before me, just moisture from the humidity of the shower if the BB is in the bathroom and even just having your Berry out using it while walking from one place to another in the rain can trigger that. I have an additional 8700g that was given to me by a coworker because the moisture dot was red and he thought it was useless. It works just fine with no problems. I have that in addition to the 8700g that I originially purchased. If I were you, I'd keep the BB that you have and purchase a battery from one of the vendors such as Seidioonline.com
or some of the other vendors that you see listed here on the forums.
Hope this helps!