Disable image flip in product image

Open custom css and find

ul.layout .product-box a .front {
-webkit-transform: rotateX(0deg) rotateY(0deg);
-webkit-transform-style: preserve-3d;
-webkit-backface-visibility: hidden;
-moz-transform: rotateX(0deg) rotateY(0deg);
-moz-transform-style: preserve-3d;
-moz-backface-visibility: hidden;
-o-transition: all .4s ease-in-out;
-ms-transition: all .4s ease-in-out;
-moz-transition: all .4s ease-in-out;
-webkit-transition: all .4s ease-in-out;
transition: all .4s ease-in-out;
z-index: 9;
position: relative;
}
Remove

-webkit-transform: rotateX(0deg) rotateY(0deg);
-webkit-transform-style: preserve-3d;
-webkit-backface-visibility: hidden;
-moz-transform: rotateX(0deg) rotateY(0deg);
-moz-transform-style: preserve-3d;
-moz-backface-visibility: hidden;

Add to custom.css

ul.layout .product-box a .back {
display: none;
}