[Samsung Galaxy S7 Questions and Answers] fireclaw316:
I've had this phone for about 2 months now, and from the beginning, it's had an issue where it would randomly freeze, restart, and get stuck in a boot loop for random amounts of time. Sometimes it would be fine after 2 minutes, sometimes it would need 10. I kept thinking this was a firmware issue - the phone WAS rooted with TWRP installed, but none of my past phones have had this issue and hardly anybody online seems to have had it, either - and just thought that maybe installing a custom ROM would fix it, but never got around to doing so.

3 days ago, my S7 went into a boot loop again, so I just decided to put it down and let it do its thing. After 20 minutes, however, it still wasn't booting, so I booted into TWRP, and cleared the cache and Dalvik cache. Another 20 minutes later, I went into panic mode and started doing Nandroid backups of my stuff. I decided that I had no other choice but to commence with finding a ROM to replace stock. In the meantime, I just plugged it in and let it keep looping, hoping against hope that it would just fix itself like it always did.

About half an hour later, I was ready to install the ROM I'd decided on. I went and picked up my phone, but all that I saw was the screen was black, and the blue notification LED was lit up. I tried holding Vol- + Power to start booting it into TWRP, but nothing happened. The phone didn't vibrate, the screen didn't change, and the LED stayed lit. I tried holding every button combination possible, for even as long as a minute, but the phone refused to respond. I tried plugging it into my computer, but Windows didn't detect anything.

Skip to today, and the phone's battery has long since died(the LED isn't lit up, so I can only assume...), and I just decided to plug the phone in for the hell of it just to see if maybe it would maybe work again. To my astonishment, 2 minutes later, the battery icon came up on the screen, but the charging animation wasn't there. When I held Vol- + Power, the phone actually responded and restarted! Though, it wouldn't boot past the Galaxy S7 splash screen, and when I tried to boot it into TWRP, it went back to being a brick. I let it sit for about 10 minutes, plugged it in, and this time tried to get it into Download Mode, and it worked!

I downloaded the Switzerland version of the G930F firmware, flashed it in Odin, and everything seems to have worked. Odin says it succeeded, but when the phone tried to restart, it got to the splash screen, and after a few minutes, the screen went black again. When I plug it in now, the Galaxy S7 screen will come up, but now I can't seem to get into Download Mode anymore(though, it DOES still seem to respond to me pressing Vol- + Power).

Does anyone have any idea what's going on? I can only seem to find 3 or 4 other threads on various forums about this problem, but none of them have any answers. People just keep saying the usual "Hold Vol- and Power to make the phone restart", but in case I haven't made it clear, THAT ISN'T WORKING.

And before you suggest that I return it to where I bought it for a replacement or refund: I bought this phone on eBay from a seller who said it was in pretty much mint condition. When the phone arrived, there was not a dent or scratch anywhere on the phone, even around the charger port, so I have no reason to believe he was lying. When I asked him about any possible problems with the phone's operational stability the other day, he says he tested it for about 2 weeks, and that he didn't notice anything.