I just had my DIR-615 rev A stop working, but the emergency flash recovery HTTP server was still operating; had a hell of time getting the emergency room to work, so it is possible to use that route.
https://forum.openwrt.org/viewtopic.php?id=37277
suggests I am not the only one having trouble using the emergency room on this model; I've had no such problems on other DLink models.
With the unit just failing by itself, I am not sure it can be trusted. I had replaced the main smoothing capacitor which was failing, but don't think that can be blamed.
Was wondering if others have seen the DIR-615 rev A spontaneously fail; for now my unit is back up and running.