Manual sharing is a way of granting access to individual records by manually sharing them with other users, roles, or groups. Manual sharing can override the organization-wide default and role hierarchy settings and give additional access to specific records. In this case, manual sharing could be the reason why only one user can see the account record, even though they have the same profile and role as another user who cannot see it. Reference: https://help.salesforce.com/s/articleView?id=sf.security_sharing_manual.htm&type=5

To grant access for the sales rep who broke their phone and needs multi-factor authentication using Salesforce Authenticator app, the administrator can generate a temporary identity verification code for them. This code allows users who don't have their verification method available to log in securely without compromising their account security. Reference: https://help.salesforce.com/s/articleView?id=sf.identity_verification_codes.htm&type=5