First, I have to ask: do you prefer to stick with FSD? Because I and others would strongly recommend you use Aurora instead.
First step you can do to fix it is to download the FSD "LIVE" installer (from Xbins). I am going to assume that you don't already have a USB drive formatted for Xbox 360 (please correct me if I am wrong).
Before we can use the Live installer, you'll need to format your USB drive. Start your Xbox, and immediately press the guide button and open System Settings on the far right tab. One of two things will happen-- you will be greeted with Dashlaunch (unlikely), or you will open the Xbox 360 dashboard. If you get the dashboard, then open settings -> storage, then format your USB drive here.
Let me know when you've done this and I'll assist you with copying the FSD live installer to the USB drive. You will either need Party Buffalo file manager or Horizon (horizonmb.com).
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