Connect to the PBX using a 9-pin female to 9-pin female serial console cable.
Use Putty or similar to console in with 115200,8,N,1
Press Enter to initialise the console
Password to enter console mode is: jannie
Reset the maintenance password using:
password man <your new maint password here>
Now you should be able to login to the web interface using the maintenance account and the password set on the end of the terminal command.
Extra notes: https://www.tek-tips.com/viewthread.cfm?qid=1783908