It's hard to give blanket advice that will be useful to you for your specific need, since different techniques will or will not be helpful depending on precisely what it is you are trying to capture in your photos. I would advise doing a few google searches for basic photography tips and how to get a good exposure, so you have a base of knowledge you can build from.
But here on OCN, check out this thread
. The first post is an excellent tutorial on photographing computers in general without any special equipment. Although the idea there is how to take beautiful photos of your computer, which isn't necessarily the same thing as documenting something that is damaged as clearly as possible for the purpose of making a claim. But the stuff in that thread about soft light vs. hard light is good info
All that being said, it's not rocket surgery
Nowadays everything is digital and you can see the results immediately, it was a lot harder back when you had to wait for the film to come back from the lab to know what you got. If it looks good on the viewfinder, or especially on the computer monitor, it is good. If it's not, fix it
So just take it slow, think about what you are looking at, and what it is you want your photos to draw attention to. High resolution and sharp focus are important so you capture as much detail as possible. Maybe you want to use hard light, which casts sharp shadows, or use soft light, which will give even and bright exposure everywhere.
I guess your original thread was deleted? There were some good pointers on photography there already if you still have them. I think you mentioned that you took a video, which is a great idea and sometimes the best way to show a subtle flaw when you're dealing with a dark subject like a shiny black radiator. You can post that to youtube and link it into a post here, or send it to ebay etc. And also not to be a noodge, but the idea of a public forum is that people post answers in the open so everyone can benefit from each other's knowledge. It's kind of against the whole purpose to ask for answers by PM