crashed instalaltion

[Macrisu]

I have a new Prestashop 1.7.6.2 (newest) instalaltion that I try to learn and I tried to use this theme. I've installed the theme and I tried to apply, but Error 500 on all may site.

Now how can I revert to the original, default theme?

[prestarocket]

set mode debug on to show errors

[Macrisu]

Set where? I get error 500

[prestarocket]

config/defines.inc.php set debug mode true : define('_PS_MODEDEV', true);

[Macrisu]

Now It works.

I suspect that I needed to disable cache and all non-prestashop modules when I tried to apply the new theme.

[Macrisu]

I've spoke too soon I've deleted the fiels from /var/cache/*

Warning: require_once(/var/www/xxxxx/var/cache/dev/appParameters.php): failed to open stream: Permission denied in /var/www/xxxxx/config/bootstrap.php on line 87

Fatal error: require_once(): Failed opening required '/var/www/xxxxx/var/cache/dev/appParameters.php' (include_path='/var/www/xxxxx/vendor/pear/pear_exception:/var/www/xxxxx/vendor/pear/console_getopt:/var/www/xxxxx/vendor/pear/pear-core-minimal/src:/var/www/xxxxx/vendor/pear/archive_tar:.:/usr/share/pear:/usr/share/php') in /var/www/xxxxx/config/bootstrap.php on line 87

[prestarocket]

I don't think it's because of the theme.