I'm learning about Import-Export Management. Please help me answer this question:

Seller (ABC Trading Co, Vietnam) offers 100 tons of coffee to Buyer (Zin Co., Japan) with the following conditions: Seller agrees to deliver the goods to buyer under the term of FOB port of Saigon, Vietnam. The goods were transported and unloaded at the port and kept at customs shed for inspection and payment of duties. The buyer was notified of the arrival of the merchandise and its location. Before the buyer picked up the goods, the customs shed (including the merchandise in it) was destroyed by fire. The buyer claims refund of the purchase price stating that buyer did not receive the goods. Is the seller responsible? Why?

I'm looking forward to hearing from you,

Thank you so much.