I replaced my old phone. I can't log in to EcoStruxure IT on my new phone

After you get a new phone, you have to enroll it in EcoStruxure IT and reset your two-factor authentication (2FA).

There are several ways to reset your 2FA, including a self-service option at https://app.ecostruxureit.com/mfa-reset/

See How to reset two-factor authentication (2FA)