I have a Samsung Galaxy Note 4. While it was charging (it was near full charge) it rebooted on its own and continued to charge. It then must have shut itself down because it was off. I could not turn it on when I checked again. I recently completed the OTA update to Android Marshmallow. That was about a week or two before this happened. I was reading why this could happen and something about a failure of the eMMC seemed to make sense.
I've tried to replace the battery with a new battery and tried a new charging cable. Neither of those worked. I read some posts that suggested removing the SIM card and the SD card and also holding different combinations of buttons but none of those work. Unfortunately the PC doesn't see the phone either (and I tried a Mac too). So I see no chance to revive the device myself, and thus have to send it in for service.
For a cost, I have an exchange pending through my mobile carrier. Should I be concerned that I can't turn on the phone to delete my data (pictures, messages, work related notes)?
I assume that I will be required to turn in my phone to my mobile carrier and they will replace the motherboard and send it out as a refurb but what if they find a simpler fix and the phone is operational without replacing the motherboard? Then my data will be there.
I do have additional third party insurance so I could mail the phone for repair to the phone manufacturer (for a fee that the insurance would later cover) rather than continue with the exchange thorough the mobile carrier. I'll still likely lose my data and there may be a long delay in getting the phone back.
I've just been told to never turn in a phone without wiping it and that is why I am hesitant. I know some people who don't turn in phones at all (they keep them or destroy them) out of concern that information can be retrieved. I've tried some local shops but when simple battery changes don't work most shops aren't interested in finding a fix for the problem. While it may be extreme, with the phone in my possession, I am still hopeful that I can find a fix whereas if I exchange it I won't have that chance. However exchanging is my cheapest and fastest option to have a working phone.