Here is a security gizmo I did to avoid any damage to myself or to the blade or to the wheels, if I happened to startup my bandsaw with its blade tension released.
La Belle Note - Startup and blade tension
It's a little sign I have attached to a big door magnet.
when the tension is released, I put it like so in front of the startup switch :
and when under tension, I put it on the side of the bandsaw, like so :
You can download it from my site if you wish to make one.