Routerboard 711UA-2HnD | Openwrt?

Hello guys, some days ago i buyed a 711UA-2HnD because i hoped that openwrt would run.

I used this manual to create the image and so on http://blog.poettner.de/2011/05/27/openwrt-trunk-on-mikrotik-routerboard-411750/

This was successfull with the rb75x, but with 711ua i just get all LEDS on. No DHCP, nothing. As i read the Free-Ports aren’t Serial-Ports?
How do i check now whats wrong if i cant connect a serial-adapter.

Does anybody having ideas ? I really need openwrt, RouterOS sucks in so many ways …
I would pay something to somebody if he can solve this.

Thank you