International shipping issue - Never seen this before

[pctech007]

Hello all, so some backstory, I was selling a very nice brand new factory sealed Apple Macbook Pro. A buyer from Russia communicated with me and he payed for the item. I always go through eBay for postage. If I don't have a box, I go to my local shipping store and they handle it for me. But for this issue, the postage and customs forms was done on eBay. Today I got a return from USPS. The value of the MacBook Pro was $3,150. Whoever was at customs in New York highlighted a few things which I do not understand and never dealt with, with any International transaction I ALWAYS left it blank since it was less than $2,500 and I  never had any return to sender. The first thing customs highlighted was AES/ITN Exemptions. What is this and how do I obtain one to send to Russia? They highlighted the US value of $3,150 as mentioned and next they also highlighted the buyers address which eBay printed this out in russian. Prior to this, he communicated with me about the English translation. So I went with it since I do not know the Russian lands. Can someone help me with this? Customs also slapped a "Return to Sender Do not reuse this customs form" sticker hence rendering this label useless. Before I call eBay I wanted to ask here first. Thank you.