I wrote a new handy script (install_1013_DP3_17A306f.sh) to install macOS High Sierra Beta DP-3 (the DeveloperSeed and BetaSeed use the same Apple download links).
The installer.pkg created by the script will simulate the App Store download and installation method and all you have to do is:
1.) Run script
2.) Launch installer.pkg
This procedure installed macOS High Sierra Beta DP-3 over a previously installed (broken) copy of macOS High Sierra DP-1. Worked for me. Please confirm.
Please note that the App Store.app downloads files to: /Library/Updates but the script uses: /tmp/ The files will be gone after a reboot, and thus you may want to make a backup of the files!
I also wrote a handy script (update_DP3_17A306f.sh) to update macOS Beta DP2-1 to DP3.
p.s. I don’t need to use the scripts to get macOS High Sierra Beta DP-3 installed because the installer from the App Store works as well.