All sounds very plausible...
The square flash cubes that rotated were called Magicubes. They didn’t use an electric current to fire, there was a spring under each bulb and the camera could push the spring up with a little lever released with the shutter. Once the spring was pushed up it released and struck a small igniter in the bulb. This acted like a cap in a cap gun and ignited due to the shock and this in turn ignited the metal in the bulb.
I can’t see how the radar would cause the ignition with this type of flash bulb.