What happened to my pomegranate tree?

Greetings all!
Last week I went to my local nursery and bought a 3-ft tall pomegranate tree in a 5-gallon pot. I also bought potting soil and consulted with the nursery manager about planting. Later that day, I planted the pomegranate tree in the potting soil in a large terra cotta pot. The root ball on the plant looked fine, and certainly wasn't root-bound. I watered the freshly transplanted tree and put it in the sun. Less than two days later, the plant looked like it was withering, and by three days after purchase, the leaves were crispy and clearly dead.
The soil never had a chance to dry out in the three days the plant survived, so I doubt that could be the problem. The pot had great drainage, so over-watering is also unlikely. The sun was rather hot one day, but the plant was growing in full sun at a nearby nursery when I bought it, so I can't imagine that could be the problem either.
A few branches still have some live leaves on them, but most of the plant looks dead. Do pomegranate trees sometimes lose most of their leaves due to transplant shock, and then come back? I doubt it, but I just thought I'd check. Any other thoughts on what could have happened?
For the record, I live in southern California, USA.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.