MQ-R no output on uart

Hello, I’m trying to test MQ-R image fetched from here: Mango Pi official website | Tiny and Elegant SBC | mqr for MQ-R board. I flashed image using PhoenixTool which went fine. I’ve connected RX, TX (PB6, PB7) to USB-<serial adapter and GND also but when board is powered (I see green LED is ON) I don’t get any output on serial port. Any idea what I’m doing wrong? Thanks.

There is more RX,TX signals (0-5). Try to connect to GPIO port 20X2-RPI (pin8 TX0 [RB8], pin10 RX0 [RB9], GND pin 6,14 …). Which version of board do you use? Tiny linux is linux with old kernel. This board is not fully prepared to work (linux version still not fully compatible with this board). Try to look at this project and compile your own linux image (armbian version). GitHub - EchoHeim/Allwinner-H616: 🔥 Linux SDK for Allwinner H616, based on armbian-build