Design:
Please explain what you mean by "won't even boot up properly". Do you mean the computer fails to respond before you see the Windows desktop? If so, when does it hang? (before or after the Starting Windows logo appears)?
Do you hear any beeps? If so, how many long beeps and how many short ones?
Do you see any error messages displayed? If so, what do they say?
Do you have any guess what may have caused the problem?
Doc