BSoD (black screen of death) is still there

Alright, my N3DSXL is BSoDing still. I have taken out the battery and the sd card and left it for a while and then tried again but it still BSoD’d. I also took it apart and cleaned all the ribbon cables with 70% Alcohol along with making sure everything was plugged back in. But it still doesnt post. Both displays work because I can go into the update menu and everything works, but it just doesnt boot. It is updated to the newest version also. I am not sure if I will just have to install a new mother board but I just do not understand why it will not boot. It worked on and off throughout the past year and a half, sometimes it would work after a few tries and worked perfectly fine while in use and sometimes could be turned on and off without it not working. But then one day in April after I tried to use it, it would boot to the homescreen and then would freeze before letting me do anything. I tried to start it while plugged in but to no avail. It has not been near magnets, nor any water damage so please, please help. I have stuff on here that I do not want to loose!