Any time you write you your phone's memory (using unauthorized tools) you stand a chance of hosing it. There are ways to erase what's in it and reinstall the proper stuff - but that's beyone most users.
I've been trying, for almost a year, to get a custom ringtone into my older Motorola phone. I haven't succeeded - but I haven't hosed the phone either (except for the time that I ran it over with my Jeep

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