Son [11] opened birthday gift early, lied about it and broke a very important rule to get to it. What should his punishment be?

Hi! I'm new, so if you spot format issues, please tell me.This all happened on the 19th.Every year we wrap up his birthday present and hide it somewhere with themed small gifts along the way that are clues that tell him where the gift is. He loves it. This year we got him a New Nintendo 3DS XL. But, his birthday is the 26th, and we set it up overnight between the 25th and the 26th. Until then, we keep the big gift in a huge drawer with a lock.The key is on my husbands workbench in the basement. We were at the neighbors (we let him stay home alone if we are just chatting with our neighbors) and while we were gone, he got the key from the workbench, and not touching the workbench is an important rule, he cannot touch it.So, he went upstairs and opened the lock, getting the 3DS and opened it, apparently forgetting to close the drawer. When confronted about it, he lied. It was under his bed. I don't know what to do. Local kids charities won't take it. What should his punishment be? via /r/Parenting http://ift.tt/2wsjKoG