Dell Inspiron 3531 not starting

Hi,

I am having problems with my 1.5 yr old Inspiron 3531 laptop , it seems to work ok until it shuts down or if it is in hibernate mode.
The problem is when it shuts down , it doesn't start for few hours, nothing appears for few hours and then it starts booting up. White charging light appears when plugged in, but no other symptoms of starting up, the fans don't spin, no hard disk noise, so nothing happens but still after few hours it just comes back up (ready to use). No issues restarting, the problem is specific to shutdown and hibernate , also it had been this way only for the last few weeks. No beep sounds, the lights don't come up as well when I try to start it.
Its quite weird as nothing happens when I press the start button but after few hours it boots up and is usable. The actual boot time etc isn't an issue but for it to start up (display DELL logo etc ) it takes few hours, until then nothing happens..

I tried removing battery, connected adapter and was holding the power button for 30 seconds or so but nothing appeared.
Tried pressing Fn key + Power button, no difference as well.
Tried reseating the memory chip, didn't help.

Any troubleshooting suggestions ?

 

Is the machine dusty inside? Try blowing it out real good if it is.