The problem was a read only file in the Framework directory. the 9.0 and the 8.5.3 versions were stepping back automatically without any notice, but after trying the 8.5.2 version, I got an error popup telling me the the plugin_customization.ini was read-only. I just had to delete all files and folders and keep only the Data directory before restarting the 9.0 installer. Everything works fine now.
Do you really think removing the error popups is a great idea!?...
Thanks for taking time to reply Daniel.