This tool attempts to extract graphic tiles from a GBA rom. GBA games can store tiles in any way they want, so there is no guarantee this (very simple) viewer will work.
If the tiles are all noise, try paging forward and you might start to see graphics. That static is non graphical data in the rom such as audio or code.
Many games compress their graphic data, this viewer does not handle compression.
Drag a GBA rom file here