Welcome and I'm sorry to hear this.
I am afraid though that this is par for the course when attempting a boar quartet - they tend to always fail. Boars find it incredibly difficult to form a functioning relationship when there is any more than two of them plus the space requirements are well beyond normal cage sizing requirements. Boars need to be kept in pairs only.
It sounds as if you have done what you can and certainly what we would advise. I am afraid now there has been a fight, then bonds are broken. As you have been able to keep a functioning pair, then keep those two together. Keep a close eye on them to ensure their bond remains intact and functioning (the result of a failed quartet is usually a pair and two singles but it has the potential to be four single piggies).
The other two, if they no longer like each other, will need to be kept in separate cages. This arrangement will need to be permanent.
Ensure the pair have a cage of 180x60cm. Ensure all hides have two exits and there is two of every item in the cage.
The two single piggies need a minimum of 120x60cm each and their cages will need to be side by side so they can still interact through the bars so not to become lonely.
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