Toshiba Satellite Laptop

Hello. I was hoping to get some ideas/opinions on how i can further proceed to diagnose a laptop I have.

Toshiba Satellite L655D-S5050
Model # PSK2LU-001003

current symptoms:

does not POST
does not boot
black screen (no lights)

upon pressing the power button
fan will spin once, stop, then after a few seconds spin full blast and remain that way forever

charger led lights up when plugged in to charger
power led lights up when turned on
no beeps (assuming this model does error beeps)


nothing in LCD screen (not even any lights)
nothing in external monitor plugged into laptop
nothing when trying to invoke external monitor with fn+f5

tested each memory stick AND memory slot individually.
tested with no memory at all
tested with hdd removed
tested with cd drive removed (cd rom makes some noise when it's plugged in. probably reading the disc inside?)
tested with battery removed

totally stumped.

i want to say mobo and call it a day but I'm never too sure and would like a 2nd/3rd opinion.

have I been thorough enough? what else can i test?


thank you very much for your time. :)