Little ones don't take to grasses when young. He needs more then grain to eat. He also needs to be in a closed chamber with 80% humidity and temps no lower then 80 with basking spot of 95-100.
He also needs to not be exposed to that cottony looking stuff in the last pic. If he eats it, it could kill him.
Cut the grass into small pieces and mix with hibiscus leaf and flower, dandelion leaf and flower the tortoise grain and any other flowers or weeds you have that are tortoise safe.