Indeed, there isn't the USB but i see that there are pins for GPIOs and GND 5V / 3v3 so i believe that soldering pins are Okay to flash after which you can to electric power on :-) Credits for the security dangers and illustrations check out StefanPatatu. He’s a https://forum-directory.com/listings12701269/the-smart-trick-of-eth%E5%9C%B0%E5%9D%80%E7%94%9F%E6%88%90-that-no-one-is-discussing