He does not have to make up for the first day; because when the sun set and he was conscious, he had already intended to fast the next day, and the pillar of fasting is abstinence, which fainting does not contradict. Thus, his fast on the first day is valid due to the presence of its pillar and condition. However, he must make up for the second day because the intention for the second day was not present, as mentioned in Al-Mabsut 3: 70.