3DS problem solving

Has it ever happened to you that the 3DS does not charge the battery properly due to "positioning" problems of the male connector that goes to the console? Well, the problems here can be 2:

1 – connector worn and dilated from use
2 – solder on the female side of the connector

Often the 2 causes go hand in hand so to fix it you have to do 2 things:

1 – press the tab indicated in point 1 towards the inside of the connector to make the connector more solid
2 – redo the welds indicated by the arrows in point 2 (usually the 2 outside break); while you redo them, try to keep the pins pressed towards the PCB, perhaps helping you by levering the charger connector itself (DISCONNECTED FROM THE POWER SUPPLY OBVIOUSLY!)

SHOULDER BUTTONS L AND R NOT WORKING

Another typical problem of the 3DS is the breaking of the L and R shoulder buttons (L seems to be the most targeted); to check if they work, keep L or R pressed in the main menu, if one of the 2 doesn't work, this message will NOT appear at the bottom of the top screen:

(if the writing appears, the key pressed that made it appear will be in "bold", in this case R)
I advise against trying to replace just the button, buy the button+wire+connector directly, on ebay you can find them both (L+R) for about 2 euros. To replace them, use the 2 ifixit guides, one for L and one for R, they are quite simple procedures.