Get it on a Consult 3 unit, that way you can get a description of the fault. I think the seat switch contacts play up occasionally. These can be shorted I think, my aftermarket rails came with a plug in module, but it showed zero resistance when i measured across the pair of wires.
Does yours have 4 yellow wires in the plug under the seat, or only two? Some have an anti dive ram in the seat, some don't.
I couldn't clear mine manually using the procedure you used, my airbag light flashed for many years before I bought the consult3, that cleared it instantly and it has never come back.