You need to search in a different direction. When you cannot answer a bible problem, you need to check your assumptions, figure out what you don’t know, etc. The answer is not that the three days and three nights Jesus spoke about in Matt 12:40-41 is parts of a day, rather you need to see that Jesus could be in the heart of the earth in at least two different locations. “Just as” Jonah was in the belly of the ship and in the belly of the whale for a total of three days and three nights so Jesus was in the high priest’s dry cistern, Pilate’s underground dungeon and then in the tomb for a total of three days and three nights, The nine or so trials Jesus went through started on Wednesday night, but He was not buried in His tomb until late Friday afternoon. Jesus was only in the tomb for one day and two nights, but He was in the “heart of the earth” for three days and three nights. The heart of the earth can and does mean more than in the tomb.
Grace and peace,
Bruce