I purchased a new 2015 15" MBP Retina in December last year. I keep it stationery on my desk and never move or unplug it from wall outlet. Battery usually shows 98% - 100% charged. Tonight while on the Internet (and not paying any attention to the light on the MagSafe connector or the state of charge on the menu), I got a low battery warning at 5% charge left? When I looked at the MagSafe connector, the light was dead. I tried shutting down and doing the SMC reset twice, but nothing. Also tried resetting the PRAM. Mac battery is now dead. I tried removing the extension cord from the charger and plugging it directly into the wall - still no light on the MagSafe connector. Would you guess it is the charger or the MacBook itself that has died 5 months after purchase? I am sure if the charger where dead the LED on the connector would not light up, but is there a condition where the LED would not light up if the charger were working? Only thing I can think of that I did recently is upgrade the Sierra System software from the previous to the latest version yesterday, but I did not check battery following that upgrade.