wp-admin/install.php not found

I think you have install a plugin which conflict with it or another plugin, could be causing the problem. You have to disable the plugin, and since you can’t log in you’ll need to do so from you FTP.

Do you have any other site in your root. You need install wordpress by it self in root.

I did install WordPress in root and still my site won′t display correctly.

I treid to go on your login page using /wp-admin and got login page fine.

Try and clear your cookies and Cache and see if you can get login page

https://www.scottishelectricgroup.com/wp-login.php loads for me