Well, be careful with the watering. Box's are pretty hardy but they are able to get rootrot, only water when soil is dry (put your finger in some of the soil to check.)
Box's dont like to be too cold, try to keep away from frost. They dont require a large amount of light either, from what ive read. But enjoy some nice sunlight, you can keep them in fairly shady areas. So shade or sun are ok.
I understand if you keep it inside for the winter because its cold, but get it out asap because like most bonsai, it enjoys fresh air. Do you see any new leaves on this yet?
You might have lost this little guy. But you never know. Keep me updated.
Anyone else
Hope this helps.
-Evan