Doing upgrade to your laptop void you warranty ?

Hello

today i put the new liquid ultra on cpu and gpu's all went fine ...
but as i power up the laptop i have no keyboard or touchpad ... i think ah! i forgot to plug back the big ribon cable ...

i check it its pluged in ... i remove it and check contact on the cable and its missing 2 or 3 litlle bar ...

i call dell and the are saying its my fault and the warranty would not cover the cable replacement ???

i always asumed that we could upgrade our laptops .... we can't ??