nook color questions, please answer :)

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so i rooted my nc and than i unrooted it, and now it dosent wanna work right, i can't connect it to my pc or download books or apps. and i have the best buy warranty and was wondering if i bring it up to them would they know it was rooted, i rooted it by sd card with honeycomb.?? would they just void my warranty or would it go through?? please answer