We run into the same problem. But solved it.
The connection using MAC address from win-box didn't work for us.
1# But you can use mac-telnet from another RouterOS http://wiki.mikrotik.com/wiki/MAC_access
, we luckily had another Mikrotik in our network.
So connect to it:
/tool mac-telnet 00:02:6F:06:59:42
-- login --
/ip firewall filter print
/ip firewall filter set 1(number of rule) disabled=yes
Disable the firewall rule.
2# It should be possible to connect using serial port, if you have it on your Mikrotik device http://wiki.mikrotik.com/wiki/Manual:Fi ... rial_Cable