You seem to be suffering unnecessarily here. Equipment does fail, there isn't anything you can do to prevent that. So the options are to swap out the device yourself or have Comcast do it. If your device is leased from Comcast and it fails, they will swap it w/o charge.
Without more info we can't really tell if it's a failed device or if there is some other underlying issue. Perhaps since your TV service is acting up too, you should just get a tech out there and get everything fixed properly? You don't need to put up with substandard service. If there is a wiring issue in your home, they may bill you for the service call, if it's all Comcast issues, you will not be billed.
Tip: If you need service, sign up for the Service Protection Plan (SPP). It's around $6 a month and you must keep it for at least 60 days after your service call. If you have SPP, you won't incur a service charge. You can sign up when you schedule an appointment.
Jamai, if there is an issue with your modem, we can swap it out for you without a tech visit. You can either swap it out at a service Center or I can mail you a replacement. Have you tried factory resetting your device to see if that improves anything?
If there is a signal issue, then it would affect your actual service and not so much your ability to connect with a particular password.