Hi there!
If you see something similar to this
http://mentalfloss.com/sites/default/files/styles/article_640x430/public/blowing-into-nintendo.jpg
even after you have cleaned contacts and eliminante every "hair node" from the cartridge port, you might have a defective RAM or VRAM. A technician with experience in replacing SMD components can replace it for you, if you provide the chip. Hope that helps.
Cheers