Changing the hero icon.

Are you modifying the DDS file? If so, you need to make sure you save it in the same format as it is in the game. For example, there are DXT1, DXT3, and TF8888 formats. The format code is contained in the XDB file, which describes the image. But I usually don't look there. Because if the weight of the saved file is correct (the same as the old icon in your case), then most likely, everything is fine.