When the Floodland program disables several U.S. satellites, we see the satellites in space and their solar panels go from lit to dark and we hear a sound as though the satellites are powering down. Solar panels do not emit light and there is no sound in the vacuum of space.
The "satellites" seen "powering down" are clips of incarnations of the MIR Space Station, operated initially by the Soviet Union and later Russia. MIR presumably had outside lighting to assist Soyuz docking manoeuvres, but the clips shown may be altered for the programme.
The grid reference (TG221442) given to Ros is not in East Anglia, but in the North Sea about 1.5km off the coast by Cromer. Also, the roads shown on the map (A331 and A211) do not cross, are either side of south London, and are nowhere near East Anglia.
Malcolm says the backdoor is a civilian comms satellite. No comms satellite would have the capability of communicating with military/intelligence satellites using different frequency allocations.