Just wondering, Is it possible to re-enable telnet access after setting up the root password?
I don’t think so. Telnet does not require a password to set up the connection. That is why it is disabled once you set a password. If it weren’t, it be a pretty easy way to gain access to the openwrt box.
However, just about everything you could do by telnet before the passwd is set can be done with a ssh shell. Windows users often use putty.
just use ssh. It is as easy as telnet.