Reset no beep

Yes there is. In the webinterface there is a 'reset to factory defaults' option. But I suppose you have no access to the webinterface due to lack of password?

In that case it becomes more complicated. One option is to use an 'Universal usb_key_func thumb'. Download the zipfile and read the embedded readme. The 'telnetd' option should give you telnet access. Unfortunately the loginless method doesn't work on a 5xx, so you have to skip the '-l /bin/sh' from the file. Which means telnet will ask for a password. You can bypass that by using the 'network_telnet_stop' script, which will stop the bootprocess before the config is applied, which means the default password '1234' is still valid. (I think). But you have to remove the '-l /bin/sh' from the telnetd line, else it won't start.

If you manage to get telnet access, come back here, than I'll find out how to reset the password.