Why is my phone not turning on?

This morning, my phone's power button and home button were not responding. I shut the phone down, which resolved the issue. Then the phone started turning off by itself. I would power up the phone to only have it shut off 2 minutes later. Then a static noise starting coming out of the speaker while it was on. It's now not turning on at all. The battery was at about 45% when this started happening. I've tried to hold the power button and volume down button...the Galaxy logo comes up and then shuts off again. And that only happens about half the time. The other half nothing comes up at all. I tried plugging it in, hoping a charge might help, but it has not. The phone is no longer plugged in but the red light is still on. Any insight would be appreciated!