Macbook pro retina won't turn on unless the charger is plugged in

1. My macbook type: Macbook pro retina 13" mid 2014, just bought in 15th feb 2015, it's out of warranty

bassed on iStatMenus Softwar it say:
Battry health: 92%
Cycle count: 304
Condition: normal

I did smc reset, pram reset, nvram reset but nothing happend
Everything is work fine, but it's should be pluge in to turn it on

Please help

2. This discussion have same issues with me, won't turn on unless the charger is plugged in but it's locked. whereas the problem is not solved. why it's locked ?