My advice to you is to soak the snake in about 1/2 inch of room temp water for about 5 minutes. That will go a long way for hydration.

Then like everyone else said, smallish meals for first 3 feedings or so, or when you can tell the snake is back to normal.

I lost a yearling for about 6 months, found it again in a linen closet under a towel. The snake looked exactly like when it escaped, maybe a tad larger. It was during Fall and Winter, so I bet he didn't do much because of the cooler temps inside the house - e.g. didn't burn alot of calories. Sand boas are very tough snakes.
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Mark