Revsearcher

Thank you very much all. I could install armbian; the problem was related to the HDMI issue that doesn't work on my device, and the led keep red. The interesting part is that I bought the device as a 4gb ram (and android shows 4gb) while it only has 1.5GB when I checked by armbian! I also took another image with a higher quality might be useful: It is almost impossible to remove the heatsink, but as I checked carefully I could see the bga pins only. Thanks. You solved my problem. I checked all the SD-card/USBs and Ethernet pins for the UART part, but I couldn't get any result.

I also have a problem with booting multitool. When I insert the sd-card, the device can't boot and is stuck with a red led. I also uploaded the PCB photos and dtb file. P.S., the device doesn't have any pin for uart/jtag. device model: topsion tp01 dtb: https://filebin.net/a6yi4grcajnqydz5/dtb