Hacking Black screen after NAND restore.

[sys64738]

Hello,
My friend has updated his Switch to 9.0.1 and after he recognises that the games are running slowly, he had restored NAND with Hekate to a earlier firmware. But now the Switch has just a blackscreen after trying to boot with SX, Atmosphere.
Any help please?

 

[Kinto77]

how did he update his switch?
Via OFW or via Daybreak/choj?
Edit: forget the above: Did he restore even boot0 and boot1? Or just rawnand.bin?

 

[sys64738]

BOOT0/BOOT1 and rawnand.bin restored.
Tried turn on with volume plus and minus holding, to access recovery menu, just blue screen.

 

[Hayato213]

Were the boot 0 and boot 1 from the same firmware version as the Rawnand?

 

[sys64738]

Yes

 

[Draxzelex]

Hello,
My friend has updated his Switch to 9.0.1 and after he recognises that the games are running slowly, he had restored NAND with Hekate to a earlier firmware. But now the Switch has just a blackscreen after trying to boot with SX, Atmosphere.
Any help please?

First off, why would downgrading make games run faster? Secondly, how is the SD card formatted?