Hello,
Based on your description it is likely that the modem is not booting up. If you could provide the Troubleshoot file from the router, perhaps I'd able to confirm it.
You can download the Troubleshoot file from the router's WebUI, System -> Administration -> Troubleshoot page.
Important note: if you decide to upload the Troubleshoot file here, I highly recommend deleting any confidential information that you may have in the configuration (except for the router's password; that doesn't show up in the Troubleshoot file)