Goodmorning,
The note 7 was recalled and this was a long time ago, in 2016.
These days phone dont explode. Overheating is sometimes possible. In your case this sounds like a bad charger or a defect in the phone.
What do you mean with a coma?
If the device becomes unresponsibe you have to send it in for repair.
https://bit.ly/2jwV3SJ