How to hard re-set a RB250GS, RB750/750G back to factory default
- Unplug all LAN and power cables
- Locate the "Reset" button, it's at the back right beside the power, use a sharp object, press and hold (make sure you can feel the press down!)
- Insert power cable, continue to hold until you see bunch of lights blinking (please be patient on this process, it may take few minutes!)
- Unplug the power cable, continue to hold at least another 30 seconds before releasing the reset button
Generally, I use this method to hard reset most the routers, so far it's been working fine!