the color of a candle is with respect to the closing price of the previous candle. If the candle closes above the price of the previous one, it will be green, closes below the previous candle's close it will be red.
If it is hollow, that candle closed higher than it opened
If it is solid, that candle closed lower than it opened
If you have a solid green candle, it means that candle closed higher than the previous candle's close, but the price on the solid green candle closed lower than it opened (AKA it gapped, and went down, but stayed above the previous candle's closing price)