Solo uses four LED lights to indicate its status during startup and in flight.

Solid white (front) and red (back):Ready to fly, standard flight configuration
Pulsing white (front) and red (back)Solo is flying under autopilot control
Flashing red alternating front and back:Controller signal lost
Flashing rainbow:Update in progress
Solid green, then turning off one-by-one:Startup successful
Solid green without turning off automatically:Startup unsuccessful, please restart Solo