Hello, I have a “New” 3DS XL with a blown diode near what I believe is the charging chip right next to the charging port. I don’t get a charging light but I do get about 5 seconds of Blue light on when I press the power button with only the side button board plugged in and nothing else, no change when I plug in the charger. The diode gives readings in both directions which is why I believe it’s blown, also I know I placed the battery in backwards when testing before putting it all back together. Fuses are good. Does anyone have any experience working with Nintendo 3DS systems? I bought a donor board and it also has the same blown diode. I think the Diode reads “C1” but I am not sure what I can replace it with. I really need someone to pull a known good one and measure it if that’s possible with diodes.
UPDATE
I removed the diode from circuit and it tested properly. I removed the nearby chip and the diode still read faulty. Then I removed the component below the diode labeled “KPH” and the diode is now testing properly in circuit. Does anyone know what the KPH component is?
UPDATE
One more thing, All of the resistors marked in this image I pulled from “John @ meche” on ifixit are showing OL, even out of circuit, they all blew?
UPDATE*
I’m a little dumb, realized my multimeter didn’t have Auto range enabled for resistance, so in reality ignore everything I said about resistors, they are fine. The issue is really the diode reading in circuit now, showing the correct value one way and the other way (supposed to be OL) showing like 2.2V. I ordered and received a “working” motherboard from ifixit and the diode on that one tests exactly the same as all of my boards do. I’m curious what the board is supposed to indicate via the power activity lights when Only the side button board and motherboard are plugged in? No SD card slot / camera / LR buttons etc… Also does the diode still say OL when you test it being the Only board with not a single other item attached?
**** UPDATE #1,376,021 ****
So, when I plugged the battery in backwards I fried the tiny 8 pin (2x4) BGA chip on the ABXY button board. I got a spare board in and now the system boots fine despite the Diode testing 2.2V instead of OL. However, I still am waiting for a 3DS charger in the mail so I can actually test charging because I am pretty sure that’s not working. One weird thing is both the spare (not always booting) system and new working board I got from ifixit both show the diode as 2.2V instead of OL. Once I get the charger I can start investigating more.
**** LAST UPDATE ****
So, if you reverse the battery on a New 3DS XL then what might happen is: the 2x4 pin BGA on the ABXY board will blow and so will the charge chip, despite showing very close diode values on all pins compared to a working board charging fine. Swapped in a spare charge chip and all is well finally, hopefully someone can glean some valuable information from my experience 
Hey! Don’t mean to resurrect this thread, but were you getting any other symptoms with your system other than it just not turning on?
Also exactly which was the charge ic that you change? not the one on the abxy board