Orange light turns on for a couple of seconds but 3DS doesn't charge

Hi, This can be a dead batteries because your indication on what the console does is the same as if there were no batteries in the console, if you have you can check wis a multimeter if your batteries charge or not, before replacing it i well check that the connection this does well between the batteries and the pins connecting your batteries to the motherboard the problem is that it can also come from the charging port in bulk your batteries still has a small amount of power but your port does not charge it wis the power supplied to the batteries, to run the fastest option is to change batteries(it is no longer possible to find official nintendo on the market, or they are priced at a console in good working order and have no guarantee of functioning, the unofficial therefore its best option, (if you buy an unofficial one, check and take one with a good amount of reviews confirm their good functioning (some sellers store their battery for too long and do not check whether it works or not before sending))

Ps: In the thread you have linked the guy recommend to have unplugged the battery and the charging cable press the button for maybe 30sec to 1min, put the charging cable maybe 10sec to 30 sec and put the battery