Can't sign in to Microsoft Authenticator app on my phone

Dear Microsoft people.

Had to delete my Microsoft Authenticator app from my phone because it didn't work.

Re-install it and now it wouldn't let me sign in (using my password).

Comes up with this:

"Please retry with a different device or other authentication method to sign in. For more details, please see this link"

The link takes me to this:

Error 400 when signing in

Getting an Error 400 when signing in?

Error 400 usually means your sign-in request with password couldn’t be processed. This can happen if:

You've tried signing in too many times in a row.

There's an issue with your browser, device, or network.

Let’s try a few quick steps to get you back in:

1. Use a different sign-in method:

At the sign-in prompt, select Other ways to sign in.

Tip: If you have other verification options already configured for your Microsoft account, you can sign in using those methods: Use your face, fingerprint, PIN, or security key; Approve sign-in with a mobile app; or Send a code to your email. Troubleshoot verification code issues.

2. Switch devices:

Try signing in from another phone, tablet, or computer.

3. Change your network:

If you're on Wi-Fi, switch to mobile data or vice versa. 

Want to avoid this in the future? 

Make your account more secure - and easier to access - by going passwordless