Things to try:
This honestly sounds like the battery is dead, but if we're to assume it's a software problem, just for starters, I would try removing the battery for a few minutes, just because it's easy. If that doesn't work, go back to recovery and wipe data/factory reset, wipe cache, and wipe delvick cache. You won't lose any files, pictures, etc. (if you have any from only 5 hours of use) from the wipe data/factory reset process, it will just reset your settings.
If you've tried all of the above, and you have searched for any other possible solutions for your device and/or OS, then I would try reflashing the ROM. You can get your firmware .zip from sammoblie .com/firmware , and you can look up instructions on how to flash a ROM onto your phone online, and feel free to ask questions here.