Ok, so you need to keep it outside all the time. Trees don't want to be moved around, especially not from one entirely different climate to another. Because that is what you're doing. It's like taking a tree from Canada to Mexico twice a day. You need to find another way to secure this tree, if you don't want it to die.
So you repotted it, that's not a minor event for a tree. Did you cut the roots back when you repotted? If you did do any large scale root cutting, you may need to take some foliage off the top (not a ton) to even out what the remaining roots are feeding. If you didn't loose any roots when you repotted, then you just need to be patient and give it a chance to adjust.
Did you wire it into the pot? If not, you need to be careful that it doesn't get moved around by wind or animals, or what have you, because when the new roots form, they'll get broken off if it moves around.
I am still a bit unsure about your coco mix stuff, I don't think I'd recommend using this in the future.
You need to not water to a schedule (every two days or whatever) you need to water when the soil is getting towards dry. Use a wooden skewer jammed into the soil halfway between the tree and the pot. Check this every day. When it starts to get dryish then you water.
If you really want this tree to survive, you need to be very careful now that you've done a repot to it. BRT's are tough, but not invincible...
. But hey, I enjoy it and will probably do it for the rest of my life 
