What did you use to jailbreak? I used redsn0w. I just did the same procedure as jailbreaking but instead of clicking on cydia to install click on custom boot logos. Don't reinstall cydia or you might have problems conflicting one another.
If using redsn0w follow the same procedures you did to jailbreak. Uncheck cydia and check bootlogo. Let it do it's thing. Your cydia will still be there but now with the custom bootlogo package. Go into cydia and download whatever logo you want. Hope that helps.