acer aspire v5-531 black screen of death

flamenco58

hi.my acer aspire v5-531 got black screen of death and there is no image neither on laptop screen nor on external display.

it all started after replacing a non-working harddrive.now there is black screen even with old hdd.

 

What i have done till now:

-checked all cables

-tested ram

-tried hard reset (by removing battery and dc power and holding power for30+ sec)

 

I have also tried to flash bios ,but failed to do so since combo keys fn+esc or alt+esc and power seems not to create any reaction( blinking power light) 

 

 

Please guide me to fix this problem.how can i flash bios on this model.i have tried many suggestion on youtube and on web but nothing seems to work

By the way it had windows 8 64bit

 

 

 

thanks