What's wrong with my phone?

I put my phone on charge and this morning my alarm never went off. I went to look at the problem and when I saw my phone, the light it shone was very very dim and it just kept on flashing the samsung name. But again, it is still very dim. Also as it's doing this the blue message light it constantly on. Is there an explanation for this because my phone is also heating up and I'm concerned that it will over heat. Please provided me with a solution as soon as possible. The phone I have is a Samsung S6 in case that helps.