Have you reached out to EZVIZ Support? Sounds to me like the Cloud may be the issue, somehow the password got changed on the DB? After calling support, if they can't help, I would remove it completely from their Cloud, in the App remove the device, then delete the account. There is a way to do what we call a Hard Reset, normally it is for bricked DBs but it should get everything back to factory settings.
⦁ SOLID RED BUTTON LIGHT; = BRICKED!!! (UPDATE: We have a solution to fix bricked DBs, try this by - Skinah or argus) (So Far (as of August 2020) THREE people to date has been able to recover their Doorbell past this point/problem, see usafltg)
It requires applying power while holding down the reset button, I have not had to do this or even tried it but all those who have stated it works.
I would call EZVIZ first, these DBs have a year warranty.