Severe powering troubles due to Micro USB power connector. It’s recommended to power through GPIO pins to prevent under-voltage issues (instabilities, boot/crash cycles). Powering situation is a little improved/masked on model S. serial console is enabled on UART2 (pin 32, 33, 34=gnd) eMMC flashing (model Tinkerboard S with eMMC) can be done the same way as burning an SD …
