First thing you want to do if verify the battery is still good, I say this because sometimes a battery can have an internal short and meet the end of it's life as you described. Check the battery voltage with like a digital/analog volt meter to make sure you still have 12+ volts. Or you could just remove the battery and take it to an auto part store and have them load test it for you (best way to test). If the battery checks out bad, replace it . If the battery is still good, re-install it and make sure the terminal are in good shape with good connections to the posts on the battery. The next thing to do is check all the fuses in the power distribution box under the hood. The owners manual has a picture of the power distribution box and a list of what circuit each fuse/relay goes to.
Hopefully you just have a bad battery. Report back what you find.
