The slim, unibody design of gorgeous handsets like the HTC One and the iPhone pose a real problem for home repairs. They're sealed together so tightly and packed so densely that even proper tools and some know-how, you might break something.
Getting at the Galaxy S4's guts, on the other hand, is a cinch. That's partly by design: The back cover pops off so you can replace the battery without any tools at all. From there, taking everything else apart by removing just 11 screws.
Once you're in, though, things are a little trickier. The internal components are modular so you can replace them individually, but they're glued into place so you'll need to work a little to spring them loose. And you better not break the glass panel because it's permanently attached top both the AMOLED display and the phone's frame.
Samsung Galaxy S4 Teardown: Easy to Fix By Design