My internet connection is down (red light in @ symbol of the modem)

My internet connection has been down for hours. The led light in the "@" symbol of the modem is blinking red. Tried to go on the modem setup and it says that the coax connection is disconnected. I checked the coax cable and it is properly connected on both ends (modem and amplifier), I tried disconnecting and connecting the coax again several times, switching modem on and off, disconnecting power of the modem for a few minutes, but NOTHING works.

Please help!!