So this happened basically directly after the A9LH Install process on 2.1 SysNAND?
Can you confirm that no errors popped up during the installation process and that the 2DS did shutdown due to the installation being finished and not manually or forced due to battery or anything else.
Which installer and which files did you use? (I assume the 2.0 installer and the files Plailect provided. Confirm this please)
If you can confirm the above parts, A9LH should be succesfully installed. Could you please list the contents on the root of your SD Card in that case? Also check you Luma folder. If there already is a config file in your Luma folder, delete it.
Because you downloaded the non-screeninit version I am not sure if you can run Decrypt9 as Arm9LoaderHax.bin, which is why Luma would be required.
Please make sure your Luma3DS is set up correctly. Then get yourself Decrypt9 and put the *bin file as x_D9.bin in /luma/payloads
If you did that try booting your 3DS while holding your X Button. If Decrypt9 shows up feel free to restore a NAND with a version above 4.5 (keep A9LH).
If you are certain luma is set up correctly (and you are using the latest version). You may have bricked during the installation of A9LH. To recover from this you would require a Hardmod. However this is highly unlikel, so please recheck your SD Card and Luma setup before.
if i remember correctly i powered off by pressing down the power button WHEN the installation was complete and it was rebooting,because i knew if it rebooted it was pointless and it was just black screen as normal.. i don't think it was the reason
with the sd folder i messed a little,changing various arm9loader and payloads,but i always putted the originals back after the test with different arm9loader.bin
for answering you questions,loading arm9loaderhax did had like 2 or 3 freeze during installation on the webpage of the 2ds,then i retried another time and it worked fine,then i shut down manually as i said. i'm 99% that it was complete and it was rebooting itself.
i certanly used the 2.0 installer
i already tried to delete the config from the luma folder before,as i readed in another thread (For information,ths 2ds now can't even do the up+L+R+a trick to recover,just a black screen without even the light coming in life,and of course the blue light led of power)
tried the decrypt9 trick you mentioned,but nada.still black screen. (do i have to put in the name of the "x_D9.bin" the .bin part or just x_D9? i already tied both and nothing)
while i was searching for some answers i seen someone having this "rei" folder that i didn'thad,and i created it manually copying the files the others had in there... so that rei is not a correct installation but a copy of what seemed to be missing
for the luma installation and other files,as i remember, i never downloadedsome latest release,as the were literally from a bunch of days ago,and i wanted the latest files before those super recent ones,because the guide is some months old and i wanted the exact same files to be sure it would run all as expected.
the screen of my sd card
https://postimg.org/image/6wj59xhsh/