Since you have replaced both the battery and adapter, and still have the same problem, it does tend to point the finger rather squarely at the charging circuit, and should be a valid RMA issue barring things like drop or liquid damage. If you are in the US or Canada, and would like to set up an RMA, you can call 1-888-678-3688 to get started. Then if you have any difficulties with the process, feel free to PM or email me, and I will see what I can do to get it sorted for you.