What model is the red light? Does it have an SD card imp? (those are a lot older and if they've never been configured, they may be unhappy with your S7 and you'll need to try an iOS device for the first connection, after which it'll upgrade)
The main diagnostic step is checking that the device shows a green LED at the end of blinkup. If it does not, then the imp did not receive the credentials.
If you do see a green light, but then it goes back to flashing red, then generally you have a mistyped password, or you have specified an SSID that the light cannot "hear" (eg it's on 5GHz, or on a channel which is not in the US/Canada range of 1-11).