Device detection error when installing custom recovery onto Galaxy S3(Heimdall Suite)

[2602]

I am trying to Flash Cyanogenmod 11 to my Samsung Galaxy S3 but I'm stuck at installing the custom recovery. After following the instructions on the Cyanogenmod wiki I got the following error after performing step 8 (On the computer, open a terminal (or Command Prompt on Windows) in the directory where the recovery image is located and type:
heimdall flash --RECOVERY recovery.img --no-reboot).

C:\Users\fergus\Desktop\Heimdall Suite>heimdall flash --RECOVERY recovery.img --
no-reboot
Heimdall v1.4.0

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Initialising connection...
Detecting device...
libusbx: error [init_device] device '\\.\USB#VID_04E8&PID_685D#6&1B368190&0&2' i
s no longer connected!
ERROR: Failed to detect compatible download-mode device.

Any ideas on how to fix it? Thanks!

 

[Jeffrey]

Try turning the phone off and pull the battery for 10 minutes. Then try the process again.

 

[2602]

Did it for an hour but it's still not working. Any other ideas?

 

[Jeffrey]

You may want to download Root Checker from the PS and verify that your phone is indeed rooted.

 

[2602]

My phone is not rooted. I am using this guide and it says at the very start that rooting "is neither recommended nor necessary." Do you think I should root it anyway and try again?

 

[Jeffrey]

Rooting is a personal decision and for those who want more access to their device. Why do you want to install a custom recovery?

 

[2602]

As I said in my first post, I am trying to flash Cyanogenmod 11 to my device.