This tutorial will show you how to put the PrestaShop website in maintenance mode.
1) In your admin panel go to Preferences => Maintenance
2) Match "No" in front of "Enable Shop"
3) After you save changes your website should be set under maintenance mode.
4) You may open access for your website for certain IP address by putting it to the "Maintenance IP" field or click the button "Add my IP" to open access for your own IP
5) To edit layout of maintenance page, you need to edit “themes\theme_name\maintenance.tpl” file.
Feel free to check the detailed video tutorial below: