I assume that is your sysnand and that you do not have emunand?
If so then yeah, you are screwed. If you want access to the eshop at all you have no choice but to update to 10.3.0-28U while it is still the most recent version. Keep in mind that every time they update NVer (when the -##X part of the firmware version changes) anyone that is not on the latest version or a CFW will be unable to sign into NNID, which means you can't access the eshop if you have a NNID linked to the system.
