that is why i am confused, I used the one image from here (armbian.com) https://www.armbian.com/odroid-xu4/ edit: what happens if the SBC starts the first time and you cut the power before hooking up with ssh - does it fall back to other credentials?

Why are you expecting this to work?

Moved to amlogic TV ox forum

@kisgezenguz you're welcome. You can check the UART RX/TX paths with the multimeter in diode/continuity mode and checking the continuity against RX (or TX) and the various SMD components. But anyway, if you read 3.3v on all the UART pins, I can guess there are three other hypothesis: * the UART RX/TX pins are correctly connected, but not to the usual debug UART. rk3399 has several uarts, so perhaps that exposed UART is not the same configured in software to be used to log the debug. * MCU_D makes me think that UART is used for the little MCU embedded into rk3399. rk3399 has two small Cortex-M0 cores for very low power tasks. So again that UART is not what you are looking for. * the RX/TX pins are just shorted to high voltage level/pulled ups on purpose (improbable) edit: I just paid attention to the schematic you posted, but it looks it does not match what you've discovered: the schematic says you should read 5.0v on the VCC pin, instead you read 3.3v. Perhaps that MCU_D connector it's definitely not the one you are looking for.

Armbian default login and password is always root and 1234. If this does not work, the image is not genuine.