Dell Precision M6500, Changing the service tag number?

Hello to all.... I Purchased a used M6500 with a bad board, but a good service tag number. Purchased a NEW MB for the same complete with base, I transferred all to new machine using the old as a donor and doing a bit of updating at the same time. Spent a lot of time on the build, never paid any attention to the service tag on the new unit. I have done this previously, as long as no tag exist, I can simply add what I need. Unit completely built, now I have found out this was a new built computer from dell that was dis assembled into parts. The main problem is that Dell Does not Recognize the existing service tag on the new MB as being valid. The seller has no problem sending me a replacement, but that takes a lot of time and effort to strip and rebuild this unit again.

Yes I have tried the dell asset.exe software (asset /s xxxxxxx) warns me of the service tag change, I go ahead and get an error. Remove the bios password (no passwords at all on this laptop or that I am using the wrong format.

Also tried asset /s /d xxxxxxx and so on any ideas out there, my files are coming off the dell ftp site HELP Please

A Thank you in advance.

hdpartman