The red LED on some remote keys does only flash once and then go out but I've yet to discover why this is because the normal operation is that is should flash constantly at a rate of twice per second. The LED on one of my own keys flashes on and off when you hold the button in while on the other (spare) key it just flashes on once
but both keys work the central locking and alarm absolutely fine.
If the red LED comes on and just stays lit with the button pressed then it indicates that the batteries are about to run out and need replacing. If the LED flashes at a slower rate of once per second then this indicates a faulty remote circuit inside the key.
The green LED on the remote receiver in the roof will come on solid green for about 1 second when you press the button on the remote if it's successfully receiving (and accepting) a signal from that remote. That green LED will only actually flash if you press and hold the pen-tip button in on the bottom of it. This isn't actually a reset button but is used to enter (tap in) the 4-digit code from one of your existing keys into the receiver unit in order to enable an additional key to be programmed in if you ever need to.
Anyway, I'm glad you got it all working in the end without too much fuss