Okay, so you have two 9020's and if one is activated and the other one not, i'd suggest that you check the activated 9020 bios to see if it is newer then the bios of the unactivated 9020. If it is newer then I would update the unactivated computers bios to at least the one that is activated and try to activate then.
While I understand your reasoning, that's not likely to be the solution. The system that is activated came pre-loaded with Windows. The system that presently will not activate was preloaded with Ubuntu. My guess is that the SLIC on the Ubuntu system is either missing or hidden. Some other Dell models will activate automatically once they're in manufacturing mode. I don't know exactly what manufacturing mode does, but my guess is that it makes the SLIC visible for one restart, and that is sufficient for the Windows to activate. If manufacturing mode is the answer, and conceptually that seems likely to me, the procedure has changed with the 9020.