OK, for the full rationale:
A, Kickoff, A-30, 5:56 (1), free kick timing (25), A=7, B=0.
A88 commits a foul for an Illegal Return when he returns inbounds, after having been out of bounds voluntarily. A88’s backward batting of the ball is legal, as well as being a legal touch of the ball (being beyond B’s restraining line), causing the game clock to be started. A88’s block on B77 is legal (having illegally returned from out of bounds does not restrict A88’s ability to play the ball or interact with opponents in otherwise legal manners). A66’s recovery of the ball is legal; thus, Team A is in legal possession of the ball when the ball becomes dead. The 5-yard penalty for the Illegal Return foul by A88 can only be enforced at the previous spot, and repeat the kickoff. The game clock was correctly started when batted by A88, since that was a legal touch of the ball, so the game clock correctly remains at 5:56.
The completion of the penalty governs the play clock for the succeeding down, which will be 25 seconds, and will start on the referee's signal. The game clock will start according to free kick timing rules.
A lot of things to process in some 8 seconds or so.