Your question was directly discussed in this Forge thread, where the designer says
"should it arise, my strong belief is that the endeavor of
collaborative Master creation, group character creation, and the
shared effort of play within the structure of the rules, being witness
to failed Overtures and whatnot, actually results in game participants
being eminently qualified to houserule their way out of a never-ending
Endgame.
Once Endgame is initiated, the Master's death is a given. So in the
event of a so-called never-ending Endgame, all we're really talking
about is how long the group continues to play before deciding the
minion characters have achieved Epilogue-conclusive scores. I believe
groups are going to figure it out."
I guess your players revolting was the expected outcome?!
Considering the rules-as-written, the key stat in being able to challenge the Master and defeat him is Love. Endgame can be triggered when
"LOVE > FEAR plus WEARINESS" (p.37)
Thereafter, as you note, any Minion fighting the Master rolls
"Minion ( LOVE minus WEARINESS ) vs. Master ( FEAR plus SELF - LOATHING )" (p.38)
Note that the Endgame is always eventually winnable (although taking longer and longer as the Master gets more dice) since each die result is 0-3. So if/when the Master rolls all 0s the Minion can win (assuming the Minion does not roll all 0s); and the Minion can never die.
Minions who are fighting the Master can give each other aid re p.35:
"contribute LOVE minus WEARINESS in dice"
and this aid is explicitly mentioned in the Endgame rules on p.40.
The minions not fighting the Master can have Overture scenes and thereby increase their love, before coming to the aid of the fighting minion.
Love across all characters is reduced when the Master kills Connections (before or during Endgame), which thereby makes the Endgame last longer. Of course the GM threatening the death of a connection can be a powerful contribution to the game. Something for a prospective GM to be aware of, summed up in this Forge thread:
"Pretty much the only pertinent place where it's useful (as in,
supportive of the goals of the game) to kill off a Connection is when
the character cares about it, the situation is a dramatic turning
point (which in itself requires several preparation scenes) and it'll
affect the character's Epilogue. In practice this means that you won't
be killing more than one or two Connections in a game, at most, and
then only near the end - such a death will then mean a critical
turning point for the PC, who will proceed to either destruction or
redemption immediately afterwards."
The Manifesto for Mastery comments:
"It is indeed tempting to Crush each and every object of Love. If you
do, you will destroy the game. It may seem reasonable that the Master
would want to destroy any resources the minions have to oppose him.
Such thinking comes of regarding the Master as a character, not as a
club. Remember that you are wielding the club for a purpose: To enable
the catharsis of the players. The only method the rules give them for
achieving that emotional release and taking the club away from you is
to accumulate enough points of Love. If you systematically rob them of
their Love points, you have stopped being a scapegoat and begun being
a bully."
Considering the difference between triggering Endgame and defeating the Master, another Forge thread included this comment which may also be helpful:
"I don't think high starting Weariness or high starting Self-Loathing
necessarily dictates who will trigger Endgame. However, high starting
Self-Loathing does seem to be implicated in who will kill the Master.
Two different things.
This is good because it means the Master has a higher chance to die in
some kind of timely and satisfying way. What I mean is, the Master
dies if (a) someone triggers Endgame and (b) a Minion kills him during
Endgame. So it's good that the game doesn't force one character to
carry the numerical weight of both (a) and (b)."
Re being Captured, this can generally only happen once per Minion. See Czege's comment in this thread:
"Regarding captures, interpret the text on page 35 to mean that
Weariness must have been lower than Reason prior to the die roll:
"When ever a conflict resolution results in a minion's Weariness
increasing to a value greater than Reason, the minion is captured by
the Townspeople or Outsiders."
So, in general, it's a one-time event. But it could happen again if
Reason were higher in a subsequent scene due to the presence of
Innocents, and it could be entirely prevented if a Innocent were
present in a scene where Weariness increased for a minion to greater
than the unmodified value of Reason (from being equivalent to that
value), and then not present for subsequent scenes where Weariness
increased."