ThinkPad T420 randomly stoped and went blank and wouldn't turn on

[plank]

Good Day Everyone, i need help

My think pad T420 have been having a problems related to power button, that is i was only able to power it on only when after turning on the powering cord with in 10 seconds i had to press the power button to turn it on. Today i was browsing you tube and my think pad hung and went blank.

I did a full power drain by removing the battery and power cord and pressing the power button for 30 seconds but after that still it did not work but
the keyboard power button did blinked when i tried to turn it.

Can some one help me what happened?