Why Won't my laptop start up suddenly?

Hi all,

Now I have.. pulled battery disconnecting ac and held down power for 30+ seconds , plugged in ac adapter w/out battery and held power button down for 15+ seconds, it shows a green led on ac adapter too, tried other known working ac adapter, no go; with or without battery the only sign of life is front power led that comes on every time. I have to pull battery an ac adapter to turn off, holding power button no matter how long doesn't work. there is no fan, no post beeps, no video... just black screen this just happened between shut down and start up next day. I'm using a Dell Inspiron 15R 5537 with an I3 and 6 Gb ram one 2 Gb and one 4 Gb, all the specs match the support web site as to service tag .. I'm outta ideas and warranty, . any help?