Hacking New 3Ds (CFW) only blinking blue once.

[westlaw]

Hi, I just got back my New 3DS XL that I lent to my brother.
It just doesn't power on anymore.
Some things I already verified:
1. The SD-Card works, I can dump the boot9strap folder onto it by holding the Key-Combo.
2. I can get into this Luma menu when mashing random buttons (L + R + ZR + DPAD-UP + A + SELECT or sth)
(Image removed, shows Luma3DS v10.2.1 configuration)
3. When pressing Start in that menu, I get to this screen:
(Image removed, shows An error has occurred: Unable to mount CTRNAND or load the CTRNAND FIRM Please use an external one. Press any button to shutdown)
4. I tried to do a CTFTransfer and then got into godmode9. It then asked me to input the date but I held the ds kinda weird so I pressed a button and this showed:
(Image removed, shows a garbled GodMode9 QR Code that is no QR-Code at all and the following text: "Exception: Data Abort (4) [newline] GodMode9 v2.0.0 [newline] 2001-01-01 00:00:17 [newline] R00: 00000000 [newline] Generating QR code...

Does anyone have a clue on how to possibly fix this?

Thx in advance!