I believe is a faulty power switch. Happened to my s3 before..do some googling,diy remove the power switch and it work like normal but you have to learn how to power it on using ext battery pack via the usb port.
I believe so too based on what I googled.. But when I brought down to Samsung Service Centre at PS and they told me its faulty motherboard. If I want to repair, it will cost me 350+ SGD. !@#$%
Boot into recovery.
Off the phone, Press and hold Vol Up+Home+Power Button.
Choose wipe cache partition.
This step will wipe your app data but not data on your sdcard and extSDcard.
Unfortunately I tried this many times, it cant reach this menu. Only able to boot into the page with that green Android.
Anyway just an update for all, I have wiped the entire OS and clean installed the latest OS from samobile, didn't solve the issue. Brought it down to Samsung Service Centre and they said that they will do their "own version" of clean install that is "different" from what can be found from the internet, thereby charging me SGD 33, didn't solve the issue either.
Based on their diagnostics, they said that it is due to faulty motherboard. I beg to differ, cus i was under the impression that they point every fault to motherboard.