My power lights turns on, but pops and turns off.

So I took a dive into the process of 3ds repair starting with my old 3ds. The bottom LCD had been worn down, so I decided to replace it. I proceeded to replace the bottom screen, but upon replacing it and putting it all back together, I encountered this problem. The blue light to indicate that the system is on comes on for about 4 seconds before making a pop noise and turning off. No backlight comes on. I’ve tried a lot of fixes for this problem, but no luck so far.