In case of the death, resignation, removal from office or other inability to act of the president so elected, the board of commissioners shall within 30 days appoint, by election, one of their number to serve as president. If more than 28 months of the unexpired term remain, a special election shall be held at the next general election to elect a person to serve the unexpired term of the president. In the case of a special election under this Section, the appointed officer shall serve until the election results are certified and the person elected at the special election is qualified. If 28 months or less of the unexpired term remain, the appointed officer shall serve for the remainder of the term.