If the input validation was impossible because all the validators were HS, what will happen?

If the malfunction is proven, i.e. the validators were indeed broken, you will not be fined and the trip will not be charged.

If the malfunction is not proven, you will be fined for "non-validation of the ticket" if you have a ticket on your phone, or you will be fined for "without a ticket" if you do not have a ticket on your phone or connected watch.