3DS XL Power Help

So I recently got my pink 3DS XL repaired. However the problem is still happening. The 3DS XL turns off at random times and requires me to hold the power button to turn it off :/ I thought it was fixed last time but apparently not. I had called nintendo to ask if they can replace it but they told me they needed my order # that I got in my email but I never got it I got a UPS label in the mail instead since I don't have a printer. Is there any way I can fix it on my own or is it a lost cause