I had a cat stuck up a tree once.
I climbed WAY WAY up the tree, grabbed the cat, sustained various lacerations, climbed down the tree, walked to with in 15 feet of my house and dropped the cat.
The cat immediately climbed ANOTHER tree, this one unbeknown to me was covered with LONG sharp THORNS, I climbed THIS tree, sustaining numerous punctures, retrieved the cat AGAIN and dropped it to the ground (10 feet or so) before I could get out of the tree, it had climbed another one.
It STAYED THERE!!!
It eventually DID come down on it's own. SO will yours.
Epilogue: Two days later my left nut swelled to the size of a cantaloupe. (from something on the thorn's of the tree I assume.) I now have a DOG, and it NEVER climbs trees!