STEP 1- Make sure that your wireless router is turned ON.If it doesn't, Press and hold down the "reset" button on the back of your router for 30 seconds.Please use a paper clip to push it for 30 seconds.
STEP 2- The reset button is inside a very tiny hole on the back of the Netgear router.
STEP 3- After resetting the device, press the "Power" button to turn it on.
STEP 4- Make sure the internet modem is connected to the "WAN" or the "Internet" port on the back of the router.
Then another Way:- I would recommend you i.e. to update the firmware on the router using the below steps:
Because the device's firmware is most likely damaged. According to Netgear, if the Power/Test LED blinks slowly and continuously, the device's firmware must have experienced problems during an update. If the LED light is blinking and the device is not performing as it should, contact Netgear for additional troubleshooting and possible repair.