Installing OpenWrt on a NXP/Freescale LS1021A-TWR board

I am now the owner of a LS1021A-TWR board and I thought about trying OpenWrt on it.
I already opened a thread on the NXP Forums but since I was still not able to boot OpenWrt correctly I am asking here. So basically I already followed the guide from the OpenWrt repository but after programming into flash it still booted the default yocto distro and after flashing the SD Card and trying what was suggested by the NXP Support I was still not able to boot correctly because now there was no console output after changeing the switch config for SD Boot.
Does anyone have expierence with that board/knows what I am doing wrong?
Thanks in advance!