So today I tried to downgrade my n3ds xl using menuhax (9.8 eu) but during the installing of the cia's it displayed an error and said I had to power down. (I checked wheter I had the correct files, and everything even md5/teracopy) Then when I started it back it was a black screen. Because I used the new sysupdater I then tried to use recover mode to update back to 10.3 but after a while it said it could not update (some error) and I had to turn the power off. I then rebooted again but I got a black screen. This time recovery mode was also not accessible so I was already panicking thinking I had bricked it. In a desperate attempt I remembered reading about removing the sd card and then booting it again. Like a miracle it somehow booted, even in 9.2 firmware. After a reformat of the sd card it seemed like it functioned again as normal. (However, I didn't attempt to install any rxtools or cfw because I suspect the 9.2 downgrade didn't complete but upgrading back to 10.3 went fine) So in short, if you think you have a hard brick you should try removing the sd card. It might be your lucky day.