Bonsai on life support - please help!

Hello! My roommate and I have been proud owners of this Brazilian Rain Forest Bonsai for 3 YEARS.

Sadly, our neighbor only watered it only once while we were away for two weeks, and all the leaves fell off.

It's been a month, but I'm convinced it's still alive. All of the branches are still green and nimble, and it's shown little buds here and there. The problem is... no leaves, no energy. It needs just one leaf to start a comeback.

It's on life support so any ideas are welcome. One thought is to prune branches to conserve energy. But we're not sure if we should do that from the main branch or the smaller ones.

Many thanks!

Can anyone offer help?

I am no expert on this species, but I read that they do not like to dry out completely which likely lead to what you are seeing. I would work to keep the soil slightly moist, but not wet. Without leaves it will not being using much water so it will need to be watered less. You may want to push a chopstick or similar material in the the root ball which can be pulled out to see if it is still moist.

What Marty said!

Your pictures look like the bark is green and a bud or two is peeking out.
It's been a month or two since you posted, so I hope this is timely. Raintree loves hot sun and high temperatures, so indulge it.
I live in far South Texas and this species is a favorite. When it's happy you can trim it weekly and still struggle to keep up. I'm sure you noticed the thorns! Clip them off as you see them or they will see you, and bite.

In the winter, it will grow ok under fluorescent light. If you don't get it inside soon enough, it will shed it's leaves but will survive a little cold temps. Try not to go under 35 º F. It will grow more leaves as it adjusts.
Hope this helps...