Website is down / can't reach the admin area because of PHP file modifications

Hi guys!
I have a problem. I followed this tutorial xhttps://kriesi.at/support/topic/see-the-code-generated-by-the-advanced-layout-editor/ and edited this code to the top of php file.

//set builder mode to debug
add_action(‘avia_builder_mode’, “builder_set_debug”);
function builder_set_debug()
{
return “debug”;
}

Now the website is down and I can’t reach even the admin area. I used another tutorial how to reach the php file through ftp https://kriesi.at/support/topic/changes-to-functions-enfold-php/ and I edited it but it doesn’t help. Pls help me with it, it’s very urgent. Thank you in advance, all necessary info will be in the private content