Action fails – what happens exactly?

We have an acting vampire with playing Shattering Crescendo with (inferior or) superior , showing one card and indicating the second on hand. The target (or one of the two targets) has a Secret Passage on it, and decides to burn it to cause the action to fail.

Question: Does the acting vampire have to pay the full cost (the second Shattering Crescendo and 1 blood) since there was no block, yet only an effect that causes the otherwise successful action to fail?
Or is "action fails" equivalent to "action is considered blocked and ended without combat"?

(Do I miss any explanation of "an action fails" in the rulebook, or is it simply not there? The only reference I could find was in 6.5.2.)

Name: Shattering Crescendo
Cardtype: Action
Cost: 1 blood
Discipline: Melpominee/Protean
[pro] Inflict 1 unpreventable damage on an ally or retainer.
[mel] Discard a Shattering Crescendo to inflict 2 unpreventable damage on each of up to 2 minions controlled by a single Methuselah.
[MEL] As [mel] above, but for 3 unpreventable damage each.

Name: Secret Passage
Cardtype: Master
Master.
Put this card on a ready minion you control. If this minion is the target of a action while he or she is ready, you may burn this card to make the action fail. A minion can have only one Secret Passage.

6.5.2. Leave Torpor Action (+1 stealth)
[...] To have a vampire in torpor attempt to leave torpor, announce the action and lock the acting vampire. If the action is successful, the acting vampire pays the cost (2 blood) and moves from the torpor region to the ready region. If this action is blocked, there is no combat (vampires in torpor cannot enter combat). Instead, if the blocker is a vampire, he gets the opportunity to diablerize the acting vampire (see Diablerie, sec. 6.5.5). If he chooses not to, or if he is an ally, then the action simply fails (the acting vampire remains in torpor, and no cost is paid). This action has a default +1 stealth. A vampire leaving torpor is no longer wounded.

The detailed play summary uses the term "unsucsessful" (Chapter IV.D.3). The version here on vekn.net unfortunately lost its structure and its links to the rulebook in one of the updates.

IV.D.3: "If action was blocked, the action is unsuccessful and blocked. [6.2.3]
a.The cost of the action is not paid. The action card, if any, is burned.
b. ....."

Hakuron wrote:

We have an acting vampire with playing Shattering Crescendo with (inferior or) superior , showing one card and indicating the second on hand. The target (or one of the two targets) has a Secret Passage on it, and decides to burn it to cause the action to fail.

Question: Does the acting vampire have to pay the full cost (the second Shattering Crescendo and 1 blood) since there was no block, yet only an effect that causes the otherwise successful action to fail?
Or is "action fails" equivalent to "action is considered blocked and ended without combat"?

(Do I miss any explanation of "an action fails" in the rulebook, or is it simply not there? The only reference I could find was in 6.5.2.) ...snip....

Short: No.
It's a case where 1.4 rears it's head.

1.4 wrote:

1.4. The Golden Rule for Cards

Whenever the cards contradict the rules, the cards take precedence.

Long:
In my opinion and logic, as rulebook says first blockers are determined and then the action follows it's succeed & unblocked or fail & blocked pattern, Secret passage contradicts that part of the rules directly delcaring the action fails even when/if unblocked. Therefore the cards by 1.4 take front stage and the action fails while unblocked, and for failed action their cost is not paid. The Player can cause the action to fail at any stage between the action declaration and resolving, using it as they wish to either allow or prevent card cycling by himself or others due to action modifiers/reactions/master out-of-turns. After Secret passage has been used, the action directed at that minion is a non-blocked failed action for possible cards and effects, so no Freak Drive (either succesful or blocked) etc.

Rambling about difference between cost and effect:
As the melniponee effect is not cost, but a requirement to even attempt the action (you cannot attempt actions that are not possible when you start them, say DOM Govern to a higher cap vampire) it never gets checked or affected in the above. This is important difference for design imho if we in the future plan on cards that say, "double/triple/quadruple the cost of actions/cards" as it does not mean one has to discard more crescendos as nowhere in the text is the discard described as a "cost". Compared to for example Rex text that directly references change in cost.

Name: Rex, The Necronomist
[Sabbat:V, Tenth:B]
Cardtype: Vampire
Clan: Pander
Group: 2
Capacity: 3
Discipline: pot pro vic
Sabbat: Combat cards cost Rex an additional blood.
Artist: Phillip Tan

The action fails: it resolves without any effet, and the cost is not paid. It's the same as an action that is blocked (it fails) without blocker, combat, nor the possibility to play cards after resolution. You cannot make the action fail once the cost has been paid.

By the bold text above, it means I cannot play Freak Drive or Zephyr after a failed action. So it is essentially an "End the action" effect?