I using 256GB SD card with fat32 format. Try boot v5.5.4 from this, but didn't it. So, try boot from 4GB SD card, was possible.

I manually put geko files onto the E:\wiiflow\codes\gct file , making sure the gct file is named using the serial ( for example 'SDVP41.gct') however after enabling 'Ocorina' then pressing 'Select' on ...