[Dakota]

All rule references from the NFHS 2010 Rules (but none were changed for 2011 AFAIK).

Originally Posted by AnonUmp

...the umpires are not to be involved in this pre-game testing. Thanks

Rule 10 Umpiring
SECTION 1 GENERAL
ART. 2 . . . Umpire jurisdiction begins upon the arrival of one umpire within the
confines of the field and ends when the umpires leave the field of play at the
conclusion of the game.

The umpires have no authority over pre-game bat testing or the consequences of that.

Originally Posted by AnonUmp

...
One bat failed the test. When the umpires arrived at the field, they were told by the association officials that player # XX from XXX HS is to be ejected from this game for having an altered bat....

Rule 5 Dead Ball and Suspension of Play
SECTION 1 DEAD BALL
ART. 1 . . . Ball becomes dead immediately when:
c. the batter enters the batter’s box with an illegal bat.

The violation is entering the batter's box with an illegal bat, not having one in the dugout prior to the game, and especially prior to the umpires' jurisdiction beginning.

Rule 7 Batting
SECTION 4 BATTER IS OUT
ART. 2 . . . The batter enters the batter's box with an illegal bat or is discovered having used an illegal bat and the infraction is detected before the next legal
or illegal pitch (only the umpire or defense may detect an illegal bat).
PENALTY: (Section 4) (Art. 2 only is cited here)The batter is out. The
ball is dead immediately. All runners must return to
the base occupied at the time of pitch. Runners would not return if they
were put out on the play.

See the part I've underlined in red. Bats discovered as illegal prior to the game by the league officials are a "nothing" as far as the umpires are concerned. Umpires rule on illegal bats that either they or the defense discovered during the game.

Rule 8 Batter-Runner and Runner
SECTION 6 THE RUNNER IS OUT
ART. 24 . . . Prior to a pitch (legal or illegal) to the next batter, if the runner was
discovered having used an illegal bat, she shall be declared out and any runners
put out prior to the discovery shall remain out.

Once again, the penalty is for use of the illegal bat during the game, not for bringing it to the park.

Rule 3 Players, Substitutes and Coaches
SECTION 5 COACHING
ART. 1 . . . Prior to the start of the game at the pregame conference, a head
coach shall be responsible for verifying to the plate umpire that all his/her players
are legally equipped, and that players and equipment are in compliance with
all NFHS rules.
SECTION 6 BENCH AND FIELD CONDUCT
ART. 1 . . . Team personnel shall wear or use legal and/or required equipment.
(1-4, 5, 6, 7; 3-2; 3-5-1)
PENALTY: (Art. 1) Illegal equipment shall be removed or made legal. The
umpire shall issue a team warning. The next offender and the head coach shall
be restricted to the dugout/bench for the remainder of the game.

Even if the illegal bat had been brought into the game, the penalty (in addition to the batter or runner being out, etc.) is a team warning, not an ejection. With a normal umpire's bat inspection prior to the game, if this bat had been discovered by the umpire, it would merely have been removed from the game; there would have been no penalty.

If the league wants to disqualify the player or take other disciplinary action, that is up to them, but it does not involve the umpires unless or until the illegal bat is used in the game.