Got a new bonsai about four days ago and over the last few days the leaves are drooping, going yellow and brittle (attached a picture).

However I have a flower that has grown and is still there during this. I'm keeping it near a window slightly open not in direct sunlight, keeping the soil slightly damp so only watered a couple of times and misting the leaves but nothing seems to be working.

It is too dry.

When surface looks dry on top, water abundantly with a fine sprayer over the whole surface until there is a steady stream of water running out the drainage holes. When a tree is dry as this one you may need to repeat 2 or 3 times with an hour in between. That Coco soil easily gets hydrophobic when got too dry.

Do you know what species it is? There are not many species that can be grown indoors and I cannot identifi it as beeing one of them. Outdoors is likelly the best option here.

Thank you for the advice. I've been worried about over watering it hence sticking with the "check each morning and night to see if the top 1/2 inch is damp and to water if not".

Unfortunately I don't, the partner got it from a garden centre and the was nothing about the name given or advice given when buying it

Looking closer on the photo. The soil is allready hydrophobic. It takes several good watering to get the soil back. Getting the tree back may be very hard.

Thank you for the help Tropfrog. I've only done it the once so far and the improvement has been massive already both on the upper leaves and the newer ones that have grown over the last couple of days while this was happening.

That is great news! Now, for right care and long term health you need to know what species it is. Go back to the store and ask what they sold you. Or maybe try the the species identificator:
www.bonsaiempire.com/tree-species/bonsai-identification

When the tree is happy again maybe Google less or similar online camera tool may help.