hp elitebook 850 g3

touch screen
intel i7-6600u SR2F1 cpu
motherboard 6050a2892401

sn# 5cg70126zz hp support not reconizing serial

laptop came from another tech and bios 128mb was missing , replaced with files from here but no joy

all voltages are ok on all indutors even cpu 1v is present

comes on , you can see the lcd turns black and after a while fan starts

i have tried soo many bios from badcaps but non of them give display..

require some urgent assistance , i have even reballed the cpu but...

nice one...