If the G15 servo did not blink 4 times, that means:
1. the ID in the code is not similar to the G15 servo
2. the G15 servo communicates at a different baud rate
To resolve problem 1, you can use 0xFE as the ID (broadcast ID, all G15 servo's will respond to this ID other than the ID set), if it blinks 4 times after you run the code, that means you have managed to commmunicate with the servo and factory reset it.
If the 1st solution doesn't work, you can use the broadcast ID (0xFE) as the ID in the code and change the baud rate (9600-500000 bps)in the code until you get a response from the G15 servo (in this case, 4 blinks).
Hope this helps. :v