Power on the router and wait for 1 minute
Press and hold the reset button for 10 whole seconds, release and immediately press and hold for a further 10 whole seconds
Leave router alone for 4 minutes whilst it performs the factory reset
Then you will be able to log in using default user name and password
If you have broken your reset button then you can use the reset via the green terminal block. Follow the process above, but instead of pressing the button just get a single wire (or paperclip) and connect GND and RST together for 3 seconds – that’s it
FYI the GND is the first one next to VCC