Root [Verizon] Root Problems

[Vision1084]

So I only have access to a mac and on Verizon. I tried to root my Galaxy S3 using heimdall. When I used the pit file and initialized I got ERROR: Failed to Initialize protocol!

Now my phone is stuck in download mode where it says Downloading... Do Not turn off target!!

How do I fix this and get my phone back to normal? I don't want to click the wrong thing and make it worse.

 

[Rolo42]

Does it only boot into download mode? Can you remove the battery and then power on/boot normally?