it looks lioke some changes have been made to the code in the index.php file that are causing the gallery not to work.
One problem I can see is that the script file includes have been moved from the document head to below the gallery, I'm not sure if there are other changes, but these edits seam to be breaking the gallery.
try reverting the /galleries/grid_fullsize/index.php file to the one from the power gallery download.