My TV will turn on for a minute and then there is a poofing noise and the screen goes black but it is still on. After about 15 minutes it will come back on and then do the same thing again.

Its broke. If its under warranty take it back... if you can't afford a new one... get this one fixed. But you won't be repairing it yourself. Sorry, but that's the nature of modern electronics.

My tv will turn on for a minute and then there is a poofing noise and the screen goes black but it is still on. After about 15 minutes it will come back on and then do the same thing again.

Model number? Is there a blinking LED light? If so, how many times does it blink? I might be able to give you a ball-park estimate of what the parts will cost for a repair.