This took me hours to find. I will avoid giving any tips as to where to find the answer, and I can assure you no engine will find the solution.
Strange, my engines finds "mate in 10" at least in 2 ways: Bc2+ and Ne5.
Clearly neither of those moves is mate in 10. Maybe something is wrong with your engine.
Currently my engine finds Nf6+! in about 5-10 seconds and gives white a substantial advantage, although black can hold on for a while with 4... Kg4.
Also, please do not double post, especially when both your posts seem to misinterpret a puzzle.
This took me hours to find. I will avoid giving any tips as to where to find the answer, and I can assure you no engine will find the solution.
Strange, my engines finds "mate in 10" at least in 2 ways: Bc2+ and Ne5.