Hardware (New 3DS XL) turns off with a pop, both screen flashes

[HSTurtle]

Title.

I recently replaced the motherboard for the 3ds, but the above symptom happens. I dug around but most said about the top screen ribbon not being properly connected, but in my case, both screen flashes. All the ribbons seems connected fine, so I fear a torn ribbon somewhere. Is there a way for me to figure out which ribbon is torn?

 

[Kubas_inko]

Try unplugging the camera ribbon. If that won't help, make sure all ribbons are properly connected or you need a new speaker cable.

 

[WarioWaffles]

iirc if both screens flash you probably have a bad digitizer. I diagnosed different screen problems by disconnecting cables on a working one, and this is all based on foggy memory, but I believe you need just the digitizer and audio ribbon cable. The camera cable can cause freezes if disconnected and you try to use it, the speakers do connect to the top screen so maybe you need the top screen too, you definitely don't need the bottom screen (just the digitizer on top of it). and I think the without the wireless there's a delayed freeze?

Either way if both screens flash that means they're getting power which leads me to believe it's a bad digitizer or audio cable, if you pull out the audio cable you can physically inspect for damage on the ends unless the hinge broke or you opened it previously I doubt there's damage to the cable in the hinge.