I was upgrading two Bolts, one was a VOX. I ordered identical 2 TB WD drives brand new and from the same source. I installed the drive into the white Bolt and it installed just fine as it came up. When I installed the drive into the Bolt VOX, the VOX started with the Yellow-Orange-Red lights on, which then changed to Red-Green lights as the TiVo screen comes up on the tv , then it returned to Yellow-Orange-Red and repeated the cycle over and over in a loop. When I took the drive out and installed in my Windows server, I found that the drive was not initialized. I initialized it and did a quick exFat format. After reinstalling it into the TiVo Bolt and starting it up again, it came up just as it should. I wanted to share this in case anyone else has this problem.