Having some issues with my rooted galaxy.

I haven't installed any custom ROMs, but for a couple years now I've been unable to update, and more recently I've been having issues with overheating, excessive battery usage, and when I try to call someone (only in the actual phone app, skype works just fine) there is no sound. I hear the beep that says it's dialing, but they can't hear me, and I can't hear them, even with headphones.

EDIT: I forgot to mention that I also cannot enter download mode, it begins to go to the screen then reboots, so I'm unable to use Odin.