macbook crashing

I am writing this for a friend who does not know a lot about computers. However, she is in another town, so I cannot look at the machine myself.

She has a Macbook that is a few years old. The hard drive failed about a year ago and was replaced under warranty. Now a new problem- her Macbook is booting to the desktop, where is holds for about 30 seconds and then shuts itself completely off. She took it to the shop and they noticed some ding or scratch (which she says happened two months after she purchased it) and they won't repair it- she will have to pay 800 for them to refurbish it. According to her, she said they did not tell her what was wrong with it (so how they can know it will be 800 to repair, I can't guess- she may have been told and it was Greek to her)

I am trying to gather some information for her and told her I would email the list. I will tell her to try to start it in safe mode first. Then try to boot from the repair disks. I will tell her to try to plug it into an external monitor to see if that works.

I do not know much about Mac OS or Macs (I use Ubuntu), so hopefully someone more knowledgeable can give more suggestions. She can't afford 800 right now and I would like to at least give her a list of things to try before she gives up on it. I thought it could be a power problem, but it does boot to desktop.

I also told her to call or go by the place so they can tell her exactly what it is they thought was wrong with it, but she is the sort who feels a serious lack of self confidence talking to tech people!

Thanks for any suggestions.

has she tried reinstalling leopard ?

will add that to the list, although she will have to have someone help her do it. i did a google search of just "pc crashing as desktop boots up" and suppose it could also be a fan problem and nothing to do with os at all. if the fan doesn't start it can cause it to shut down to avoid damage. that is, of course, nothing she can even begin to fathom. i want them to tell her exactly what it is they will be refurbishing for 800 dollars, though, before she commits.

it may very well be a hardware failure, as i would think the mac shop would have tried the other things, but who know?

it saddens me that people who don't know much about their computers are at the mercy of tech support.

thanks.