Claim of refund and compensation from online events supplier for breach

Hello,

We hosted a digital online event with a supplier and paid 50% advance and provided them with an invoice-based PO for their services.

During the event, their hardware crashed and their CEO requested us to cancel the event and postpone it after 2 weeks.

With no options during the event and disappointing used experience throughout the event, we had no choice but to take their recommendation.

We canceled the original event and rescheduled for the new date they proposed. During the NEW date event, only 300 people participated instead of the 1800 registrations.

Can we request a refund and cancel our PO based on the fact that less than 20% of the users showed up after their first experience?