iFixit's staff are really helpful. If you need help with something, I'm sure they would be happy to help you. (Perhaps I should have asked them first :D)
From personal experience with my older iPhone 3G, if it's broken to the point that it actually won't work properly (i.e., a faulty Home button – an iPhone without a Home button isn't much use), just take the thing apart and do your best to fix it. My rationale is that if it doesn't work anyway, you have nothing to lose. Even so, I take care while repairing things. [http://www.ifixit.com/Device/iPhone_5#guideList|Check out this page] to find out if iFixit has a guide to show you through your problem to the solution.