Advent 6311 laptop problem

Hi, guys. I have an advent 6311 laptop which has worked fine until one day it wouldn,t
turn on. My local coputer shop said it was the motherboard and that it wasn,t worth
fixing.
I found a working board from an online computer shop saying they are removed from fully
working machines so carefully replaced it,double checking all connections are correct.
It now boots up ok and I can access my computer,control panel etc but cannot get an
internet access,wireless or otherwise.I find also it wont play any cds or dvds.It says
there is no audio output device.I have used my original hdd, cpu and ram.
Can this all be caused by the same fault.
Any ideas would be greatfully appreciated.
Byronboy.