AirPort Express orange yellow light problem and not discoverable at all

My AirPort Express is showing a permanent orange light. Every ~5 minutes it blinks green once and after this I get continuos yellow. The AirPort device is connected via LAN to my Linksys WRT-160NL router that is configured with DHCP enabled - is supposed to give and IP to the AirPort. The AirPort is undiscoverable via LAN or WiFi. If I try the hard reset procedure, all I get is flashing yellow led after few seconds but no other effects.