I have a Samsung galaxy s3 that I bought back in July. Awhile ago, I was having some issue with the battery, but once I let it fully drain and then recharge, it seemed ok. Yesterday, my battery dropped to 50% within a minute of unplugging it. This morning, my battery went from fully charged to zero and shutting down within one minute while still plugged in. Help please! I haven't had my phone that long. What can I do?