@customerservice-- Yes, (from what I have seen from working on these) it would seem that the hard drive has gone bad. When the iPod is starting up, place it to your ear to hear any heavy clicking noises. This would mean the drive has gone bad. If you hear basic humming/whirling, the hard drive should be okay.

@wisenwealthy-- The red X on a 6 Gen iPod classic means the hard drive has failed and will no longer work. On earlier models, it would show the "Sad iPod" icon.