Three successive tones, then a five-second pause (repeating): RAM
doesn't pass a data integrity check.
The MacBook Air doesn't have any user serviceable memory, so it's a logic board issue. Since you cannot boot, there's really no other option but to take it in for service.
It's likely that Apple will want to replace the logic board for a large sum of money. I suggest looking at a reputable 3rd party repair shop. I have used Rossmann Repair Group in the past with great success (not affiliated, just a client)
He even has a YouTube video with your exact problem and how he fixes it; it's technical, but full of good info. Caution: he's from NYC so his language is typically colorful.
You should take the computer in to your local Apple Store or Apple Authorized reseller. It may be that the milk (or milk residues) finally dripped down enough to short out parts of the motherboard.
Don't try lying to them; fess up to the milk spill and maybe you'll get lucky. In any case, you're looking at what is likely to be an expensive repair (involving the motherboard, keyboard, and anything in between).
Electrically yes, physically not without an adapter.
Only the physical layout of the pins and metal end that connects to the Air is different. However, with the MagSafe to MagSafe 2 Adaptor ($10) lets any original sized MagSafe adapter slim down to work with the new thinner Mac-side of the MagSafe 2 connection.
Best Answer
The three short tones with a 5 second interval between sets is indicative of a RAM failure
From Apple's support document: About Mac startup tones
The MacBook Air doesn't have any user serviceable memory, so it's a logic board issue. Since you cannot boot, there's really no other option but to take it in for service.
It's likely that Apple will want to replace the logic board for a large sum of money. I suggest looking at a reputable 3rd party repair shop. I have used Rossmann Repair Group in the past with great success (not affiliated, just a client)
He even has a YouTube video with your exact problem and how he fixes it; it's technical, but full of good info. Caution: he's from NYC so his language is typically colorful.