You've discovered the bane of home repair. You have to make your best guess.
All I can offer is some old advice about how to choose which part. Here goes.
-> If you know it's that part, replace that part.
-> If you can't tell which part it is from say a few parts, replace the cheapest part first.
Hope this helps,
My Acer Aspire 4730z laptop quit deader than dead. No charge or nothing when plugged in.
I took it apart and looking at the power plug and wiring all look fine. No burn marks, bad connections, etc.....
I bought a new charger ($8.99) and it fried as soon as I plugged the charger to the computer and to the wall plug. (The original charger still has a green light once plugged in so I thinking that this charger is actually okay).
I am left with the thought that the motherboard is bad...
HOW DO I DETERMINE IF IT IS BAD ??
The laptop is 3.5 years old and I hate to put too much more money into it (motherboard on ebay is $45).
It is a good experience to disassemble the laptop for the first time.