Welcome to the Community Forum, it's always great to see a new face here. I'm sorry that you are getting a TV Anywhere error stating your username or password is invalid after your TiVo replacement.
I've checked into this for you and have resynchronized your TV Anywhere services on the main server and also sent new signals to reset this on your TiVo. Please reboot your TiVo and retry this. If you are still having the same issue, you may need to remove your devices and then add them back on.
Let me know how this goes for you and if you need for me to add a device change back on.
Need help changing SIM card? Find out more about activating your 4G ready SIM. 4G SIM Swap Help