Pu-Erh Stale?

Hello everyone, About 3 years back when I was living in Thailand I bought a 2 year old cake of Pu-Erh and a few small bird’s nest pu-erh. I tried both at the time and they tasted great. I quickly finished the nest style but let the cake sit for the past few years. Recently I decided to finally dig into the cake more and it was stale, a very flat taste with little to no vibrance that it had previously.

My question is does anyone know how to bring life back into the Pu-Erh? I have not kept the Pu-erh sealed in a container, just in my cabinets with the rest of my tea wrapped in the paper in which it originally was sealed.

Thanks for any help!