First, there is no 30-30-30 method. Never do that.
Don’t do it for 15 to 29 seconds. It is not correct.
The correct way:
After the router boot (the router have to boot up), simple hold down the reset button, the first led (power LED) will start to flash. It will flash once per second. 3 seconds later it will flash twice per second. 8 seconds later it will flash 4 times per second.
Now release your finger and wait the router to reboot.