They look at the machine and guess what parts to replace. Then they give an estimate with the highest cost estimate but if the machine takes less parts then the bill is less and the owner gets a break.
In your case I'd be swapping out the motherboard as my best guess what part to change.
My N130 fell from my desk about a week ago, the screen showed all the colours of the rainbow and start humming loudly.
My first port of call was to check the screen connection after receiving some advice. I unscrewed the screen, removed it and checked the screen connector to see if it was connected. Even though it was secure I re plugged it in and turned it on. No result. Then, I disassembled the entire thing, removed the RAM, unplugged all the wires, removed the fan, unscrewed that silver thing that sits on top of the CPU, removed everything except the hard drive and CPU and left it all in pieces on my desk for about an hour.
Came back to it, reassembled it all and then disassembled the screen, took it out and removed the tape that secures the connection between screen connector cable and the connector socket, just in case it was interfering in the connection in some way. Put it back together and powered it up. Still nothing.
Then I got an idea from something I'd once read, put it on it's side and left it on for about two hours, with the battery in. Nothing really happened. About to give up hope, I decided it was time for some pain. I hit the keyboard roughly on it's left side and also hit the screen. Turned it on and then cried for joy as I saw the familiar sequence of lights flash on, the sequence it has when working. It changed again, but the Samsung boot screen came alive. The screen had lines of jumbled colour in the centre, running from top to bottom and covering the second 's' in Samsung. The blue loading bar froze about a third of the way in. I left it for a few minutes and then forced it to shut-down by holding the power button.
Turned it on again, only the power light came on. Tried again. The last three lights came on. Tried again. It booted up properly, past the Samsung boot screen, past the windows loading screen and onto the password display(still with the garbled lines in the middle. The little box came up telling to plug in the charger or change the battery. Stupidly, I plugged the charger in and it froze. I had to forcefully shut it down again. It's not booted since, but every time I turn it on the sequence of lights change, it's almost as if how fast and how hard I hold the power button changes it.
This has been quite a long post, I didn't want to miss out a single detail just in-case it helps figure out what the problem is. Can anyone come up with a solution?
I don't want to keep restarting and forcefully shutting it down because I'm given to understand that it can have detrimental effects.
My net-book is a Samsung N130, Windows XP, 1 GB ram, 1.6ghz Intel Atom CPU, 160 GB HDD. If you want more specs, just ask.