Sounds like Samsung preempted your problem in a way that didn’t require your call to Customer Support at all…
I have tried googling both faults. The first one - switching off every three minutes - brought up a very large number of hits, but with no solution. As I’ve said, the only good thing that Samsung did was to tell me the correct solution for that.
The second - defaulting to ‘ext’ with an unremovable error message brought up an even larger number of hits, but all relating to attaching a hard disk to the TV, or to errors with Samsung hard disks.