Long Version: My friend lend me his "not working" 3ds to see if i could fix and hack it, about not working, when his sd card was inserted the blue light just flashed and de 3ds turned off imediatly, this also happened if the 3ds didn't have a sd card altogether, but if i inserted just the sd adapter the blue light stood on but nothing happened, just black screen, the strange thing is, when i put MY sd card (the one i used to hack my 3ds, with all the files, games, etc) it worked fine. One small problem: My friend had already downgraded the 3ds when he tried to hack it (that's when it stopped working), so i couldn't get the nand backup. Other than that i followed the 3ds.guide tutorial from the downgrade point on step-by-step. everything worked fine until the a9lh installation, when i pressed select to full install it said i didn't have the otp.bin file, so i used otphelper to get it (i switched the arm9.bin and arm11.bin files from the tutorial for the ones that come in the otp helper .zip for that, but after i got the file i switched back), then i tried again and when i pressed select everything went fine, it said the green sucess message and i pressed a button to turn off the console, but when i try to turn it on, no matter how (with/without sd/adapter, holding L/R, etc), now the blue light just stays lit forever and the console stays in a black screen. Short Version: This happened after a9lh instalation: it said that the instalation was sucessful but when i try to turn the console on the blue light stays lit but the screen stays black. I don't have the nand backup and i used otp helper to get the otp.bin file (i did this while i was in 1.2.0). Don't know i this helps in anything but i have another 3ds with luma, a9lh, etc and a 11.2.0-something U nand backup, but the problematic one is european. Apreciate any help and sorry for any grammar errors.