If you are handy with tools and careful you can disassemble this beast but know that it is not a general user repair. The guide on this site works quite well, you'll need to add in a bit of the HDD removal so you can fish out a cable but it does just fine. If you are not handy then I priced out the repair from a Mac repair guy in town and it would have run $180 in labor, and then the PSU costs. For that you can pretty much score a working newer model on eBay.
At the very least you might want to open it to get your HDD out. My worry is not the disassembly, but the reassembly.