Did you try and connect the booster to the router after resetting? Ie press and hold the wps button on the booster until it flashes amber, then do the same on the router.
Ensure that the booster is not placed where the WiFi is weak, but somewhere halfway between there and your router.
If you still can't get it to work you will need to contact Sky to discuss your options. You may be able to have it replaced, or have an engineer visit, depending on your package.
