Hi, Couple of months ago my RN104 failed to boot after a power failure. I didn't really know what happened, but after much googling I stumbled upon this forum which has been super cool. I picked up a ttl usb serial to plug into the back. If anyone is curious. There's 4 pins (in the shape of s square): GND/RX/TX/3.3V. GND:If you have a multi-meter, you can figure out which oneby newbienard - uBoot