The blinking underscore means telnet was able to connect to the port. As for the other error, are you sure you are forwarding the port correctly.
Try following portforward.com's guide for your router (Found here). Just ignore the part about static IPs, And only open the port you want, there is no need to open a range that large.
i used to have a smaller range, untill i realised that many apps use ports that cannot be changed, so i took a bigger range.. ..