I had a controller which lost Web UI access, but was pingable and has SSH Access.
The second controller works fine. I have reseated the controller but am not able to bring it back online. No ping, Web UI doesn't recognize the controller and 7-digit display shows SE-88 which should be "Power-on default".
I would agree, if you have done all steps in the kb, then you will need to call support as it is likely a hardware issue. I will say, if you can reseat the battery and the external HIC(if it has one) following the process in the kb that might resolve your issue.
Are you receiving a specific message when you try to online via SANtricity? It is likely you will need to submit a support case so we can take a look at why the controller wont come online. It sounds like it may need a controller replacement but NetApp support should determine that to be sure.