Bricked Wii - gradual failure, no mods

I've tried to find information about bricked Wiis, but I can't seem to find anything related to unmodded consoles. My Wii bricked a couple of weeks ago. I bought it from a friend a few months back. It refused to boot on the first day (full brick), but I left it on, and after several hours it booted successfully. It has worked fine since then, short of a few brick boot ups here and there. After awhile, we decided to just leave it on 24/7 to prevent further problems. It did occur a few times since, but it always recovered. Every once in awhile, though, some of my channels would give me a corrupt error, but it seemed to fix itself. Fast forward to a couple of weeks ago, my buddy decided to turn it off overnight, and it hasn't worked since. Odd thing, though, is that I took it somewhere for a day (worked just fine), and when I came back home I left it sitting in my bag for about two days. After hooking it back up, it worked for about two more days until it bricked. It's displaying the common full brick problems - power button works on the console and Wiimote, boots to black screen, Wiimote doesn't sync nor can I power off with it, games can be inserted/ejected. The console is 100% bone stock/unmodded, and no attempt has ever been made to do so. What could have caused this? What sort of hardware failure could have happened? Everything online is telling me that without any sort of backup installed, I'm completely out of luck, but am I really? Could SaviMii potentially help? I plan on trying to take apart my GC controller if I can ever get past the damn wing screw. I would rather not install a mod chip, and having Nintendo repair it is out of the question. Any info you could give me would help me millions. Had to happen after investing so much time into Skyward Sword...........