AlexDW, вы знатно накосячили
В файле upload\install\opencart.sql ваш коммит, касающийся пропущенных значений для английского языка, ломает установку
Строка 347, запрос
INSERT INTO `oc_banner_image` (`banner_image_id`, `banner_id`, `language_id`, `title`, `link`, `image`, `sort_order`) VALUES
(79, 7, 1, 'iPhone 6', 'index.php?route=product/product&path=57&product_id=49', 'catalog/demo/banners/iPhone6.jpg', 0),
(87, 6, 1, 'HP Banner', 'index.php?route=product/manufacturer/info&manufacturer_id=7', 'catalog/demo/compaq_presario.jpg', 0),
(94, 8, 1, 'NFL', '', 'catalog/demo/manufacturer/nfl.png', 0),
(95, 8, 1, 'RedBull', '', 'catalog/demo/manufacturer/redbull.png', 0),
(96, 8, 1, 'Sony', '', 'catalog/demo/manufacturer/sony.png', 0),
(91, 8, 1, 'Coca Cola', '', 'catalog/demo/manufacturer/cocacola.png', 0),
(92, 8, 1, 'Burger King', '', 'catalog/demo/manufacturer/burgerking.png', 0),
(93, 8, 1, 'Canon', '', 'catalog/demo/manufacturer/canon.png', 0),
(88, 8, 1, 'Harley Davidson', '', 'catalog/demo/manufacturer/harley.png', 0),
(89, 8, 1, 'Dell', '', 'catalog/demo/manufacturer/dell.png', 0),
(90, 8, 1, 'Disney', '', 'catalog/demo/manufacturer/disney.png', 0),
(80, 7, 1, 'MacBookAir', '', 'catalog/demo/banners/MacBookAir.jpg', 0),
(97, 8, 1, 'Starbucks', '', 'catalog/demo/manufacturer/starbucks.png', 0),
(98, 8, 1, 'Nintendo', '', 'catalog/demo/manufacturer/nintendo.png', 0),
(79, 7, 2, 'iPhone 6', 'index.php?route=product/product&path=57&product_id=49', 'catalog/demo/banners/iPhone6.jpg', 0),
(87, 6, 2, 'HP Banner', 'index.php?route=product/manufacturer/info&manufacturer_id=7', 'catalog/demo/compaq_presario.jpg', 0),
(94, 8, 2, 'NFL', '', 'catalog/demo/manufacturer/nfl.png', 0),
(95, 8, 2, 'RedBull', '', 'catalog/demo/manufacturer/redbull.png', 0),
(96, 8, 2, 'Sony', '', 'catalog/demo/manufacturer/sony.png', 0),
(91, 8, 2, 'Coca Cola', '', 'catalog/demo/manufacturer/cocacola.png', 0),
(92, 8, 2, 'Burger King', '', 'catalog/demo/manufacturer/burgerking.png', 0),
(93, 8, 2, 'Canon', '', 'catalog/demo/manufacturer/canon.png', 0),
(88, 8, 2, 'Harley Davidson', '', 'catalog/demo/manufacturer/harley.png', 0),
(89, 8, 2, 'Dell', '', 'catalog/demo/manufacturer/dell.png', 0),
(90, 8, 2, 'Disney', '', 'catalog/demo/manufacturer/disney.png', 0),
(80, 7, 2, 'MacBookAir', '', 'catalog/demo/banners/MacBookAir.jpg', 0),
(97, 8, 2, 'Starbucks', '', 'catalog/demo/manufacturer/starbucks.png', 0),
(98, 8, 2, 'Nintendo', '', 'catalog/demo/manufacturer/nintendo.png', 0);
Первая колонка, а именно banner_image_id - первичный ключ с AUTO_INCREMENT
А в вашем добавленном коде для второго языка значения в ней дублируются.
Получаем 500 ошибку на третьем шаге при установке