New 3DS XL won't start, no LEDs at all

Hello, few days ago I entirely reshelled my New 3DS XL. (Shell, buttons etc, from white to black).

I tested it and it worked correctly, but I forgot to put the metal ring in the hinge. So I unshelled it one more time, but after that my New 3DS XL won’t start again.

The is no led at all, even when I put the charger.

  • The battery is ok, I tested it.
  • The power button also works correctly with the multimeter. I don’t think this is the issue.
  • LEDs also works correctly when tested with the multimeter.
  • The fuses are both functionals too.

At this point I’m unable to find the problem.
Also, when I wanted to test the upper LCD before screwing the shell, I accidentally flipped the battery for at least 1sec. Idk if this can damage the motherboard.

Can someone suggest something ? I have a multimeter.

Any help is welcome, thanks !

PS: I’m french, sorry if I wrote wrong words.

You actually made the contacts touch, reverse plarity? because obviosuly with the shell on you shouldn’t be able to do this, I don’t imagine they would have installed a polarity protection diode on the board given the case design so pehaps IC damage… tbh i haven’t done a lot of board work on 3DS’s so couldn’t tell you which IC to check.

If i remember right though, there is a microswitch which the back plate presses on, if that switch isn’t pushed down then the console won’t boot (at least if i’m remembering right) so might be worth checking that… and please somebody correct me if i’m wrong

Your English is perfect! better than mine (and I’m native :wink: )

Hey, yes in fact screwing and unscrewing the shell is annoying so I just made contact with the battery but in the wrong way. Rookie mistake lol.

But, reverse the polarity is that bad ? I didn’t know but if yes, maybe this is the problem
I shall check on the net about the polarity protection you said.

The first time I tested without the shell it worked correctly, tronics in a ytb video also did this so I don’t think that the shell must be closed for the console to work :grin:

Is there a method to check if the motherboard is dead or not ?
Thanks :smiley:

Yeah, if there is no polarity protection present (which I don’t think there is going to be) then you can pretty much bet that something will get wiped out, and it will likely be the first IC the +/- battery terminals are connected to. So your gonna wanna take it apart again and buzz out in continuity mode where those go, it will likely lead you to the charging IC I’m guessing, then you’ll wanna test for shorts on the surrounding caps and whatnot as that would be the most likely failure in this case.

Maybe I’m completely wrong man, I just thought i saw what looked like a switch when the back plate is removed but maybe it’s not a switch at all, maybe it’s just a flexible indent or something to preload the backplate or something :thinking:

I watched tronic’s video with the yellow pikachu new 3ds xl and I have the same issue !
Btw even tronics can’t fix this, apparently there is a short with the ground, exactly like in his video. The ground is totally connected with negative due to a small chip hard to replace. I thought it was normal but not.
I think, like tronics I have to replace the mainboard :grimacing:

Sorry, I’m not sure what you mean by this? If you mean ground is connected to battery negative pin then that would be normal.

I just watched his vid - In the case of tronicsfix vid, he had a faulty EMMC IC, but just because you have a short on this rail doesn’t automatically mean it’s the EMMC in your case. As you saw, the ribbon connectors were damaged etc so looks as though it’d been through the wars, so odds are it could have been something along those lines which caused the EMMC IC damage in his case. 4.2V battery voltage wouldn’t make it’s way directly to the EMMC (reverse polarity in your case) so I don’t really see it (though could be wrong) Unless of course the reason your having your current issue as a result of misaligned or incorrectly connected ribbon which subsequently caused your short (which would align with Steves vid)

Anyway. over by the EMMC IC is a couple of caps, I would imagine the short to ground is present on one of these caps? if yes, then choose a ground point for your probe (and keep it the same throughout) put your other probe on the “positive” side of one of these shorted cap/s and measure the resistance to ground to the digit, record the reading - Now do the same thing over at the caps by the charging/BMS IC (sorry I don’t specificallt know what this IC is off the top of me head) and record the resistance reading. If the reading is lowest at the EMMC IC (caps) then the fault is most likely there, if it’s lowest at the charging/BMS IC then the fault is most likely there.

Anywho, I’m not at all sure if the EMMC IC (data) is paired with the SoC on 3DS like it is on Switch, if not you can buy these chips preballed (if your new to soldering this makes it easier) and replace it if the EMMC IC is infact your issue. (though you will likely have to use some homebrew method to get the FW on this IC after if in fact you can)

And of course if it’s the charging IC / BMS you can replace them fairly easily, and I imagine theyr’e commonly avaliable.

Hopefully someone who fixes DS/3DS more regularly can chime in and can confirm or deny what I’ve said… Sorry I don’t have a 3DS board open out of case atm otherwise I’d check which rail it is of yours which is shorted, I’d take a wild guess it’s 3.3V or maybe 1.8V (and if that’s the case, then faults like this could be any number of things)

Okey, so what I heard in his video isn’t what tronics really said. My oral comprehension isn’t good yet so I think I confused everything, sorry! Thx for explaining me. Later today, or tomorrow, I’ll try to do what you just recommended me to do.

I’ll try that too !
So your gonna wanna take it apart again and buzz out in continuity mode where those go, it will likely lead you to the charging IC I’m guessing, then you’ll wanna test for shorts on the surrounding caps and whatnot as that would be the most likely failure in this case.