I had some screen related issues while installing stretch (using the non-free firmware iso because of wifi) on my Acer C740:
1) In the beginning of the installation, installer was not able to automatically detect screen resolution and asked about it. I choose the 1024x768 option and rest of the installation went fine. 2) When I rebooted after the installation, only one line of flickering text of grup boot menu was visible on the top of the screen. After a few seconds the boot started and the screen went totally blank. I blindly gave disk crypt password and after a few seconds got proper lightdm login screen. 3) I added line GRUB_GFXMODE=1024x768 line to /etc/default/grub, updated grub, and rebooted. 4) Reboot now gave me proper grub boot menu screen, but after I pressed return on Debian GNU/Linux line, the screen went blank again as it did at (2). Again I blindly gave disk crypt password and properly got lightdm login screen. I can live with that, but just wanted you let you what happened. Earlier I had installed GalliumOS on the same laptop without screen related issues. -- Juha
