Recommended reading:
1. Create resource account & assign the license
2. Configure Exchange mailbox properties
3. Turn off password expiration
Setting Password never expires is a requirement for shared Microsoft Teams devices. If your organization prohibits passwords that don't expire, you'll need to create an exception for Teams device resource accounts.
4. Disable 2FA for the resource account
Microsoft Teams Rooms do not support 2FA. You may need to exempt the resource accounts from your conditional access policies. See https://learn.microsoft.com/en-us/microsoftteams/rooms/conditional-access-and-compliance-for-devices
5. Test the sign in of the Resource Account
Use this tool: Teams Rooms sign in test to test that your Teams Rooms resource account is configured for successful sign on.
Note: Device hardware registers to the resource account it signed in to, in the Teams Admin Centre (TAC). If the hardware is moved to another room resource account, it needs to be unregistered first in TAC to avoid sign-in and permission errors.
The change can take up to 48 hours to update on the device.
Alternatively, delete the old resource account and setup a new one, and factory reset the hardware before signing in for a quicker resolution.