I don't believe there is a way! As your motors make the noise! Although, ( I have never tried this ) not sure which craft you have but on the P2's any of them, when I run diagnostics, if I UNPLUG, the com wires to each speed control, I hear nothing on startup, BUT, I'm not sure doing this will mess up upgrade or not? Like I said, I NEVER TRIED IT DURING UPGRADE! So try at own risk!
If you do try let us know, if it works!
Would save a lot of people a lot of headaches! Just a theory but not sure if it will work, because I believe the ESC units upgrade also in the process! But I do know the craft will startup with esc unplugged!
Hope this helps!
J Dot