How to enable external display on touchbar MBP with broken screen

I have a very recent (this year) MacBook Pro with touchbar and 4 USB-C ports (not sure the exact model, as the screen doesn't work). Somehow while going through airport security yesterday, something got between my screen and touchpad and cracked the screen right below the camera. The screen is mostly dead, showing just a few pixels along the break.

Before I take it for repair, I'd like to access some things on it. I normally use it with external monitors via USB-C to HDMI adapters, but when I try it now, nothing is happening. The machine chimes when connected to power. Powering on will run fans, and the esc key appears on the touchbar, but that's it. The external monitor stays in powersave mode. I've tried connecting an external USB keyboard (Via USB-c adapter) to see if Cmd+F1 would enable mirror mode and enable the external monitor, with no luck. I've tried closing the lid while the keyboard and monitor are attached, again with no luck.

Is there any way to get the machine to use the external display prior to logging in?

Update: I was never able to get the machine to work with an external monitor. My employer sent it to Apple for repair; when it came back, everything was fine and all my files were intact. It would have been helpful to grab a few files off the machine before I sent it off, but in the end nothing was lost.

There is two solutions that I can recommend for you.

First, a very generic one where you need to close the screen lid.

1. Hook the LCD display to the Mac with the appropriate adapter
2. Hook up the external keyboard and mouse (optional but recommended)
3. Boot the MacBook with the broken screen, then close the screen during boot

This will automatically boot your Mac to use the attached external screen

In brief: Restart your system and then close the lid so the lid sensor acknowledges the lid is closed your external display should automatically become the primary display.

And, Second, if you have another Macbook with you, you can try this crazy idea too

If you have easy access to a second Mac and the right cable to connect the two (e.g., Thunderbolt to Thunderbolt, USB-C to Thunderbolt, USB-C to USB-C, etc.), you could:

1. Connect the two Macs with said cable
2. Put your damaged MacBook Pro into Target Disk Mode by holding down its "T" key while you turn it on
3. Turn on the second Mac while holding down its Option key so you get to choose which partition to boot from
4. Choose the system volume of the broken MacBook Pro

This basically lets you use the intact second Mac to boot into the system that is installed on the MacBook Pro with the damaged screen. If there are indeed any software or hard drive issues with that first Mac that prevented you from logging in, you are now able to see and potentially address them.

For more details on Target Disk Mode, see this guide.

I had the same problem with macbook pro 2017. The only thing I would recommend for the above steps is to have your power cable connected to macbook. In my case it was not switching to external monitor while closing the cover. Connecting power cable solved it.

After you plug-in the USB-C cable, the screen should be automatically mirrored, if you are on the login screen.

If this doesn't work, you need to visit login screen somehow. To do this, you can take help of voice assistant:

1. Enable voice assistant by pressing the power button 3 times. Now you can hear all the labels and UI element when you press Tab or hover over by touchpad. You can use this to open the login screen.
2. Once you are on the login screen, it will be automatically mirrored on your external display.