If it was 4-5 days in a box it would need to be trained to the bright light. It could be one of the problems. 5 days without water would also have been a stressor. Orme de chine does translate to Chinese Elm.
We do have them here but it is not one that I have grown or am familiar with.
These might be helpful.
https://www.bonsaitoolchest.com/v/vspfil ... se-elm.pdf
It sounds like the bonsai may have been in box and probably not watered for about 5-6 days.
When you watered, did you soak the tree. Chinese elm cannot get really dry . If the soil was really dry, you have to water it well. Bonsai don't have a lot of soil so not a lot of water reserves. If the center of the rootball was really dry and you only watered until the outside looked moist the center could still be dry .
Try soaking the pot in a bucket of water until the bubbles stop. The plant soil should be thoroughly moistened then. Take the tree out and let it drip dry on a rack but do not let it sit in a saucer full of water.
Chinese elm is a high light plant but given that it was in a box for 5 days or more, it may have been a little too much light too soon and that could burn some leaves.
Scratch the bark with your finger and see if the inner bark is still alive. If it is then maybe there is still a chance to save it. You will have to remove any branches that look dead and the dead leaves.
Pay attention to the tutorial on how to water your plant. Over and underwatering are the major causes of plant failures.
If the roots and inner bark is still intact and the tree was taken care of in time, and taken good care of from this point forward it may take a while but could come back.