I can tell from your simple description that you're unable to log in at the FileVault login window. You force restart your device which makes it boot into the Password Reset Assistant. Although you reset the password, you still can't pass the FileVault login window. In this case, you're suggested to turn off the FileVault and decrypt your device.
Here is how to do it:
1. If you're at the FileVault login window, press and hold the power button (or Touch ID) until your Mac shuts off. Then, press the power button again to boot into the Password Reset Assistant.
2. Select "My keyboard isn't working when typing my password to log in" and click Next.
When prompted, enter your login password to turn off FileVault and start the decryption process.
3. If successful, you'll be prompted to restart your Mac.
4. On the next boot, your Mac should immediately boot macOS and then load the login window. You can also boot into Safe Mode if desired.
If you're still unable to boot into macOS Safe Mode or use other startup key combinations, check if a firmware password is set on your Mac:
1. Turn on or restart your Mac while holding down the Option key.
2. If you see a padlock and a password field, a firmware password is set on your Mac and is blocking you from using macOS Safe Mode. Otherwise, if you see a selection of startup disks and/or the ability to connect to Wi-Fi, a firmware password has NOT been set on your Mac.
