Ok, so two of them I was able to recover using the instructions you gave @Moors7, the last one I brought home, not able to get into safe mode, in DFU mode, tried particle update, says successful, reboots and gives a hard fault with SOS, put back in DFU, tried particle flash --usb tinker, says successful, reboots and gives a hard fault with SOS. I found another discussion here: Photon in RED SOS hard fault mode, unable to put into safe mode. Looks like this one may be down for the count, unless a new development has come up since this post.