Rescue Mode, Debian, UEFI

[Rob]

The Debian installer manual says that you can access rescue mode with accessibility. Quoted text:
# # #
5.2.9. Expert install, rescue mode, automated install
Expert, Rescue, and Automated installation choices are also available with accessibility support. To access them, one has to first enter the “Advanced options” submenu from the boot menu by typing a. When using a BIOS system (the boot menu will have beeped only once), this has to be followed by Enter. Then, to enable speech synthesis, s can optionally be pressed (followed again by Enter when using a BIOS system). From there, various shortcuts can be used: x for expert installation, r for rescue mode, or a for automated installation. When using a BIOS system, they must be followed by Enter. 
# # #
Okay, that's great, but what about a UEFI system?
I installed Debian, and I was watching the braille display during grub installation. It said
Running 'grub-install dummy'
Why is it running dummy instead of /dev/sda1 or whatever the efi partition is?
When booting the installed system, what comes up is a grub rescue prompt.
I thought I would try this fix:
https://superuser.com/questions/1154866/unable-to-install-grub-in-dummy-on-debian-stretch-in-dell-precision-5510
Can you still insert your Deibian installer flash drive, press tab, and type
brltty=auto rescue/enable=true
when it comes up?