New 3DS buttons and touch not working

Hi!

I have a strange problem with my New 3DS.

My buttons and touch stopped working - well not all buttons, C-stick and ZR ZL still work without issues.

I have disassembled the 3DS and put the motherboard in an another New 3DS, but that did not help.

The funny thing is, that buttons are not damaged, as i can get in to the update menu (L R A UP) they stop working after the system loads, and because the touchscreen is not working either, I can't force an update. So this must be a software issue.

Is there a way to force an update without the touchscreen or other buttons?

Cheers!