I have an even worse problem.
I DID have priiloader, I DID have Bootmii installed to boot2, I used the NAND formatter to restore a fresh 4.1 file, and I STILL don't get the system menu.
It asked me for location settings, time, date, etc, and then the screen goes black. Nothing happens. The system menu never starts. If I turn it off and then restart, it takes me back to the setup options, as if I haven't done them.
I have an LU model, with a modchip installed.
Is there anything else I can try???? Can I load some kind of cIOS installer straight from Bootmii or something???? Please help.
Edit: The plot thickens. After the fresh NAND, I can't access Priiloader (since I wiped it I assume) or BootMii. When I hold reset and power, it flashes by very quickly, and then proceeds to the setup menu again. Am I done for????