What went wrong with Russell's car at Silverstone?

Where Mercedes and Lewis Hamilton were ecstatic after their victory at the British Grand Prix, George Russell slowly disappeared with a painful DNF at Silverstone. On Saturday, the Briton still managed to secure pole position at his home circuit, but during the race he had to abandon the battle due to a problem in his car. Meanwhile, technical director Andrew Shovlin explained the problem with Russell's W15.