The flickering on the brake pad light sensor is due to the extremely basic and rudimentary design of the pad sensors:
A simple copper wire with some insulation is fitted in a hole into the brake pads. When the brake pads reach its limit as they are being consumed by the brake discs, the insulation of the copper wire is disolved. The copper wires are exposed very slowly, creating intermitent ground as they touch the pad or the disc.
That is why at the beginning the light comes on and off. As the wire consumes itself, is more exposed, making constant ground. By this time the brake pad warning light should remain constantly on.