I succeded in installing Openwrt on my RavPower WD03.
During configuring I decided to update openwrt first, using the prescribed procedure. Since then It doen's seem to work anymore. The lights are coming up, so the hardware seems ok.
I can start a reinstall using tftpd, kernel is loaded and rootfs is searched as described, but after a reboot of the WD03 I cannot open the configuration page.
Maybe I should go back to the original firmware first and then try again, but I didn't save the old files.
I know badzz offered a solution for this in [SOLVED] Procedure for going back to OEM firmware for RP-WD03 but as I am new to this forum I don't know how to reach him.
I hope someone can help me out.