everyone is responding about VZW warranty claims, but if you read his post again you will see he sent it to Motorola directly...
i think there is a much higher likelyhood that they will actually turn it on, see its modded, void the warranty (since they are the ones that locked down the bootloader anyway) and just send it back the way it is (sorry man, just my gut feeling)...
i don't think they could legally keep your phone since its yours, they just won't fix it or they will charge you out the ass to fix it since you voided the warranty (btw, i don't think rooting and modding should void a computer's warranty, especially since rooting it didn't break your screen)