Nintendo New 3ds xl Permanent blue light, black screen

I bought a faulty new 3ds xl, at this instance the problem was that the console doesn't turn on due the battery.

Everything look fine, shell, screens, charger, digitalizer...

After change the battery for a new one, the 3ds was able to power on, but just a blue light with black screen (The blue light won't come off until I press the power button for 5 seconds).

I had a look into the SD card, and it looks like there isn't any homebrew in the console.

After that I saw a few tutorials talking about a problem with the WI-FI module, I had follow all the steps but without luck (I have to mention that all the components look in a great status, in my opinion, I think that I was the first one that opened the console).

I have tried to go to the Update Screen Pressing and hold L + R + (dpad) UP + A + Power, nothing happen.

Few more tries, I decide to remove flex by flex to check if I got any other kind of light, but having always the same result, black screen with permanent blue light. Also, I tried to power on the console without any more components that the Motherboard and the module for the battery, with the same result.

For last, I saw a few videos using the ntrboot method (flashcard) to try to bring it back the system, but, when I press the button combination (X + Select + Start + Magnet(for sleep mode) + Power) and I release the magnet, the 3ds just turn off. With this method is the only moment when the console do anything different, but I wasn't able to go far away.

I'm very newbie in this area, and not sure what else I could check. Do you have any ideas?

Thanks in advance!