my $.02 worth on this.
I'm one of the people on this thread that had a problem with my recorder.
The night mine died, I used an
Energizer energi to go battery pack that has separate 5v, 12v and 20v outputs. It was the first time I had used that battery with my DR-680.
When the recorder was not working properly that night, I started checking all the cables. I pulled out the power cable and plugged it back in. I don't know for sure what outlet on the battery pack I originally had it plugged into, as it was dark and the battery is black with small lettering on the outputs. So, I think there's a chance that I briefly sent it 20v rather than 12v.
Mine was still covered by the Tascam labor warranty. So, I happily sent it to Tascam and paid the parts cost to get it fixed. I still love my DR-680. So, keep that in mind when assessing the reports of problems with the Tascam DR-680.
Now, I have taped off the 20v output on that battery pack.