There are some things that cause the theme becomes blank when installed, are: Downloading a theme that is deficient or corrupt, the possibility index. file (403) are not in any folder, and other things that are unknown.
How to cope with the current theme is the result blank installed is to upload the theme files in zip format manually, on the theme folder is located.
Open the folder-website (public_) / po-content / themes / themes-related, the next step select all files in the theme folder and delete.
Still the same location, which is on the theme folder to delete the file. Now do upload it manually, then extract the newly uploaded theme.
Now go back to the tab of your admin dashboard / theme / all-theme, and reload or refresh your browser. If you do it correctly, then preview the themes that you have uploaded will appear there.
The latter, on the tab where you access cpanel hosting, open the menu “thrush” and clean the thrush. This is to avoid wasting your hosting capacity.