I have the same problem.
I downloaded LF_v6.1.36-2.1.0_images_IMX8DXLEVK.zip and I mounted on SD card "imx-image-full-imx8dxlevk.wic" (7GB size)
.When I plug the SD card and I switch on the board, led D3 start blinking (I suppose it is resetting continously).
Dip switches of SW1 are set to 1101.
i don't see any data on the serial port. I only see COM port 12-13-14-15 even if the board is powered off.