It looks like my issue is not the same as the one above. Sorry, I thought I was searching a list of stretch-only bugs and didn't notice the old date on this one. Also the vga=normal workaround does not work for me, so probably not the same issue. While I'm writing this though, I should note that the Help screen did allow me to get to the boot prompt (seems like an odd way to get to a boot prompt). I tried boot: install vga=normal fb=false hw-detect/startpcmcia=false bootkbd=es netcfg/disable_dhcp=true desktop=kde but it still hangs immediately. I also found
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=838320, but in that case the user seems to have gotten to the mirror selection screen so that appears to be a different issue as well. I guess I'll file a new bug report.