Plug in a usb mouse and keyboard. Then try these startup key combinations:
Try an SMC reset:
https://support.apple.com/en-us/HT201295
Try starting up in Safe Mode:
Use safe mode to isolate issues with your Mac - Apple Support
If neither of those work boot into Recovery and Reinstall Mac OS.
About macOS Recovery - Apple Support
Try Single User Mode (hold command-s keys)
https://support.apple.com/en-us/HT201573
At the prompt, enter this command:
/sbin/fsck -fy
Press the Return key.
This will check your directory and report that it was OK or repaired. Then enter this command to startup normally:
reboot
If none of those work make a Genius Bar appointment for a free diagnostic:
Plug in a usb mouse and keyboard. Then try these startup key combinations:
Try an SMC reset:
https://support.apple.com/en-us/HT201295
Try starting up in Safe Mode:
Use safe mode to isolate issues with your Mac - Apple Support
If neither of those work boot into Recovery and Reinstall Mac OS.
About macOS Recovery - Apple Support
Try Single User Mode (hold command-s keys)
https://support.apple.com/en-us/HT201573
At the prompt, enter this command:
/sbin/fsck -fy
Press the Return key.
This will check your directory and report that it was OK or repaired. Then enter this command to startup normally:
reboot
If none of those work make a Genius Bar appointment for a free diagnostic:
MacBook pro frozen at login screen
