When you can't download the game you just have to have follow this guide to replace your Wi-Fi card.
Step 1 Top Panel
Push the Spudger into the crevice between the grated top panel of the Xbox and the bottom body with the rubber feet.
Pull back on the spudger like a lever, keeping it pressed firmly into the crevice.
Slide the spudger along the separation you have created between the grated panel and the bottom body of the Xbox.
Periodically pull back on the spudger like a lever, keeping it pressed firmly into the crevice.
Continue sliding the spudger along the perimeter of the left grated face of the Xbox.
Pull the top panel off.
Step 4 Wi-Fi Card
Remove the 11 mm screw left of the green wifi-card using the T9 Torx screw bit.
Firmly grip the green Wi-Fi card and pull it out of the Xbox.