Agent in Fargo, ND

I (buyers agent) sent in a PA, and was verbally told I was getting a counter back. However, what I initially received back was a fully executed PA, and the box to check counter offer was not checked (approx 1 hour later). I messaged the listing agent and thanked them for accepting the initial offer as written. Within minutes of this text I received the counter as well. Do I try to hold them to the original signed PA, or honor the verbal, and subsequent counter? I have informed my client of the signed PA, but advised it may need to go a legal route, as there are still things not agreed upon.

*Broker states technically we have a signed agreement. Wants to still try to work with them to reach an agreement, without using the technicality, even though he acknowledged the other agent messed up.