It had been threatening for some time, with a tendency to automatically click through the menus - cured by rotating the top control wheels a few times, probably dirty contacts. Now, however, a more sinister fault has appeared the dreaded "Camera error. Turn power off then on."
Searching on the Internet this appears to be a fairly common fault and may be related to a small spring attached to the shutter mechanism. The cure would probably cost more than my battered camera is worth, but a get by fix is to switch off the Front Shutter Curtain. It clatters when used, but it works a bit.
The camera did well to survive as long as it did under adverse circumstances. I've taken many thousands of shots and it has been carried around on a bicycle, dropped and generally not looked after. The paint has long gone on the corners and the strap looks ready to snap. It did have the good sense to continue working until I had invested in a new Sony a6500.
I've enjoyed the NEX 6 immensely, I had become tired of lugging a heavy DSLR around my neck. The NEX freed me from the volume and mass of the DSLR while it allowed me to shoot using my old film era lenses, the excellent electronic view finder enabling easy and precise focus. I have always admired the compact and beautifully made Leica rangefinders, but they were way out of my price bracket. The NEX provided a similar shooting experience and I suspect that the Sony sensor was as least as good as that fitted to the more prestigious marque!
So it has more or less died. It has served me well and I have no regrets!