Frozen MacBook on login screen

Use an external keyboard & mouse. If both the internal Keyboard & Trackpad have failed at the same time it is most likely a hardware issue especially if the external devices work. Take the laptop to Apple or an Apple Authorized Service Provider to be repaired. I'm not 100% certain, but I believe the Trackpad Cable is the most likely cause of the problem. This can be a very difficult problem to troubleshoot since the problem can be very intermittent and sometimes can even be temporarily "fixed" by rebooting the computer or even reseating the Trackpad Cable. I would insist at the very least the tech replaces the Trackpad Cable since it is inexpensive and very easy to do (labor cost will be more than the cost of the cable).

Hi frederik_kv,

Thanks for coming to Apple Support Communities for help today with your frozen MacBook Pro. Have you tried forcing the Mac to power off by pressing and holding the power button at least 10 seconds? Then, press power and see if it boots up again.

Let me know if that doesn't work.

Have a fantastic day!