No Wi-Fi and internet on Box 12

The issue happened suddenly when we lost wifi. We called service but they couldnt help. I tried restart, reset and whatever is suggested by everyone. When i check, i see that the modem lights in the back of it blinks for about a min and then goes off, power light goes red. Then the cycle continues. Once in a while the wifi comes back for few second. So, it is gone before i can actually do something with it.