My xperia sp doesn't turn on just vibrates!!!!!!

[BarcaSoldier]

Please help me guys.Last night my xperia sp suddenly turned off.I had 86% charge.Now it doesn't turn on just vibrates when i turn on and nothing happens.But if i try it again after 30 minutes or 1 hour it starts.But as soon as the phone gets locked or go to sleep when its idle the phone just turn off.It just vibrates.Its not the normal vibration when i turn on the phone.It's like 3 quick vibrates and it doesn't start.If i plug the charger it just keeps vibrating but doesn't start.Please Help me guys....

Sorry for my bad english.

[_alexdon_]

Connect to wall charger,let it charge for 1 hour,force shut down.

http://userguide.sonymobile.com/referrer.php?region=global-en&product=xperia-sp#!Turning-on-or-off-t...

After that,normally turn on the phone.Remove any task killers,battery savers you have.