I too have been having the same issue with all three of my BD-JM57C players since June 19th. Didn't use any of them on the 18th but did use one on the 17th; everything was fine. When the issue presented on the 19th, I switched it out for another one; everything was fine; then the next day when I attempted to use the same player, the issue presented; so I tried a different one; same issue; then I started to think it was the TV; so I moved it; same issue; then I began to think that perhaps Samsung was no longer supporting the player, so I reached out to tech support and found out that the J-series players are having issues, that tech support is aware of and working on. Just completed a chat and there's still no solution or timeframe for one.
Swapped out two, similar issues, then the third downstairs did the same. I'm going to try them again since it's been a few days and probably a firmware issue and maybe they'll have downloaded a fix
Oh my goodness!!! Same problem with my BD-J5700 Blu-ray Disc Player for about the last week or so (on or about 6/20/20). The machine just keeps cycling on and off. Won't stay on to allow any type of reset...just a repeated, incessant noise like it is trying to read a DVD even when there is no disc inside the tray. We tried unplugging it for a while, but no change.
We are aware of the boot loop issue that appeared on certain 2015 Samsung Blu-Ray players and are offering free mail-in repairs to customers who have been impacted. We encourage any customer with questions to contact us directly via chat or call at 1-800-SAMSUNG.