I appreciate you cannot see anything on screen but do the fans start is the hardrive indicator flickering , can you hear anything , if you can and you have an external monitor on another PC plug it into laptop and see if anything appears on that screen , if you have nothing at all power wise ,try the following
unplug power adapter , remove battery wait 10 mins , after 10 mins keep your finger on the power button , then put in battery then power adapter and try again