I would not do melon, they cannot digest high sugar foods.
Is he sleeping a lot? It usually takes them quite a few days to adjust to a new home.
Also, if it's too hot or too cold it can encourage them to sleep a lot.
What kind of lights are you using and how long are they on? Russians need a lot of light and for 12 hours a day. They need a basking spot of 90-95 but they also need cooler areas so they can regulate their temperature.
What's the humidity at? They like it fairly dry, but it's also really important to soak him for 20 minutes several times a week.
One more tip for you, you'll want to cover the tank with something so he can't see out of it. Tortoises dont understand glass and will relentlessly try to run into it, and it also makes them feel vulnerable.
I personally don't hibernate my russian because it doesn't get cold where I live. If you do decide you want to hibernate him, you'll want to take him to a vet and have him checked out first. An unhealthy tortoise will not survive hibernation.