Thank you for making your first post regarding the issues you are having resetting your Hub 3.
Please follow these exact steps and let me know how you get on:
Disconnect all unneeded ethernet cables from the rear of the Hub.
With the Hub Powered on use a paperclip or similar (I use a mobile phone SIM Slot tool) and do a pinhole reset.
Depress the pinhole switch for a timed 60 seconds then release.
DO NOT reboot the hub but allow it 5 to 10 minutes for it to boot itself up.