The flashing green internet light typically means the connect box can’t connect to UPC internet; either because it’s not provisioned for your account/box or because the cable or connection isn’t good. However, the wifi not working shouldn’t be related to that, so maybe the settings have somehow become corrupted.
There’s a button (marked reset I think; I’m too lazy to walk over and check mine!) below the four yellow ethernet sockets. Press it and hold it for about 10 seconds. The box will then perform a reset. Note: this can take ages (like up to half an hour). Once it’s stable, try again.