Hey brm,
Thank you for reaching out! I am very sorry for the frustrations you've experienced. I would recommend completing a PIN hole factory reset with the steps here. Please hold in the PIN hole for 30 seconds so it completes a reboot. You should then be able to access the modem via WiFi (after connecting to the network) or ethernet on your PC with these steps. If that doesn't fix it, your best bet is to get in touch with technical support directly for further assistance.
Cheers,
Tony | Community Mod.