Started playing up a while back -- would get stuck in a weird bootloop for a while, where it would show the Galaxy S4 logo with coloured stripes all over it, or the screen wouldn't even come on at all, or it would vibrate continuously. Now it refuses to boot into normal/recovery mode whatsoever. I'm guessing it's a hardware thing. I've heard that leaving the wifi on whilst charging can cause these phones to overheat and eventually fry the insides?
Anyway, oddly enough I can get into download mode ('Odin mode') just fine, and it stays on there stably. I used Heimdall to get my PIT. Annoyingly, I have the "KNOX WARRANTY VOID 0x1" message, which sucks because I definitely haven't done anything to void the warranty myself!
I can't see any way of doing so with Kies, Odin or Heimdall -- but is there a way of simply downloading EVERYTHING off my phone? Like, just a straight up dump of all of the partitions. Or at least the user data ones. I have a bunch of stuff on there (cryptocurrency wallets!! sentimental text messages!!) that I'd really like to backup. I know that if Samsung ever reply to my many service requests and fix my phone, they'll probably wipe it before sending it back / send a replacement.
tl;dr: Can I back up my S4 mini's data partitions from the download mode? Can use Linux or Windows tools.