Inspiron 1520 out of warranty motherboard replacement

ok, so i have a slightly upgraded Inspiron 1520 I bought jan last year for uni work. 5 months after it started not booting up (just the power light coming on, nothing else) every so often and randomly locking up`, gradually getting worse, until it wouldnt boot at all. after spending a few hours on the phone i was told my motherboard was faulty and that it would b replaced. And it was, and my laptop started working as normal again.

Now a few weeks ago, it started this behaviour again. randomly not booting up/locking up. i know whats wrong with it, and I am confident that if i was able to get another motherboard i would be able to replace it myself. i have looked around on the dell site, and havent been able to find any information on replacing my motherboard. what are my options? would it be possible to get a motherboard from somewhere which i could replace myself?