I've been trying for a couple of years to figure this out. I was in the middle of using the machine when I noticed the battery was running low, even though the laptop was plugged in. I tried to re-seat the power adapter, but nothing worked. The battery ran down and the laptop shut down.
Since then, I've tried replacing the AC adapter (had to order a third-party one, but specs matched), replacing the DC-in power jack (135W), and generally looking to see if there are any obvious breakages anywhere visible to the eye. No joy.
This laptop was a gift and originally came from India. It is not under warranty and I can't find anyone locally (Japan) who will service it.
Any ideas of what else I can try?