Help with brittle shrub/tree

Fremont CA

Description

Does anyone know how to help my plant? It's a juvenile moon lagoon eucalyptus, an evergreen shrub from Australia or southern California climate. Roots seem healthy, the stem trunk is green but the leaves have turned brittle and dry and fall off easily. I took him out of direct sunlight and have tried not to overwater him but I'm not sure why his leaves are turning brittle. Should I prune his leaves? Any tips appreciated.