Hey Denise,
Well, I bought my phone through Best Buy, so going to the AT&T store (my carrier) only got me the 'well, did you buy insurance?'...so no help there. Samsung gave me a choice to either mail it in or bring it to one of their repair /customer service facilities. The only one close to me is LA (I'm in San Diego). In either case, there was no guarantee on what would happen; I was told there is a checklist of things they do to see if the problem fixes itself (yes they said that), and one of those steps is to factory-reset it . Now, we all know that turning a phone on and off, turning it on in safe mode, and factory reset wont do anything for burn in, but tier-one techs aren't paid to think. So, either you do it at home before mailing it in, or they do it at the store you bring it to. Either way, you'd better have your Google account set up, and a backup made using the Samsung 'Smart Swtich' software. Important to note that if you do take Samsung up on its warranty (one year from time of purchase) it will be up to them on how to handle the problem. In my case, they said they might try to repair it (!!!), or if they do send another one it might be a refurbished unit as well! Plus, its going to be about a ten day turn around *IF* everything goes well. They didn't use those exact words but I am relaying the jist of the conversation. So, if you go Samsung, the 'free' route, you're gonna be without a phone for 10-14 days with no guarantee of what exactly will happen...so, I decided that that was not an optimal option for me. I have the AT&T insurance plan for my phone, and theirs is VERY liberal. Basically covers everything, including burn-in. I'll have to pay a deductible, split up over several mobile phone payments, but one I invoked the insurance claim, I got a NEW phone in two days, and was able to keep both for 10, so I had time to set everything up on he new one at my own pace. There's several different ways to transfer data over easily, so I was able to get up in running on the new one in a day.
Once burn in appears, there's no fixing it, and it DOES happen to Note 4s when texting, AND it gets progressively worse. If you can do without phone for a couple of weeks, send it to Samsung and take advantage of the free warranty service, if you are within one year of purchase. If you have insurance and cant do without a phone and don't mind paying a deductible, go that route.
A couple of suggestions - don't use the stock messaging app. Use a messaging program where you can change the background. I have no proof of this but I think the yellow-orange-white combination of the stock Samsung messaging app is when helped cause the burn in (that in combination with high heat). I use Textra and changed my background to Black and Dark blue. The keyboard, which was the most prominent thing that you could see on the burned in screen, is now two shades of light gray. Second, make sure your lock screen timer is relatively short, so the phone turns its screen off in like 30 second of you not touching it. Keep track of heat! I use Cooler Master to monitor temp and shut off background apps. Seems to be affective. If at all possible keep the phone on a cool surface or if sitting around in front of a fan! I know that sounds goofy but anything to keep it cool will work. Finally, there's an app called 'screen burn-in tool'. This will NOT fix the burn-in like it claims, but what it can do is show you very clearly the extent of your burn-in and if you have any. The program runs through and displays a series of full-screen colors. You can pause on any color by tapping on the screen. You can then hold the phone at different angles while paused on that color to see how bad it is or if you are developing burn-in.
So, knowing all this I'm going to be very careful with how I use the phone. I'm really hoping it doesn't happen again, as like I said in my earlier post I like the Note 4, and since the Note 5 is basically an IPhone 6, I don't see myself going backward, so I'll have to find a new phone to jump to when the time comes. Let me know what you decide on doing, I'd be interested to hear your experience if you use the Samsung-warranty route.
Have a good one,
~ D