Updated sysnand to 10.3 - was I dumb?

I have a US N3DS XL (with a sysnand backup of 9.0) now on sysnand 10.3. I updated it after seeing that gateway now supports 10.3, but I think they meant emunand only.
Now when trying to enter Gateway mode (put in Zelda, launch Gateway SAV, press "A", boot into Gateway menu) it freezes on Link.

Do I have to restore my sysnand? If so, how do I do that if I can't get in to the Gateway Menu?

Thanks in advance