Default Samsung galaxy fit (gs5670) not identified in download mode


I have a problem with my Samsung gs5670. I installed Cyanogenmod 11 via Clockworkmod but I can't add a Google account. Because of that I want to flash the original Samsung firmware via Odin. The problem is that my mobile is identified by the PC when it normally starts but it isn't in the download mode so I can't flash it. How can I solve this problem?

Sorry for mistakes I am german

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