Schumacher, a seven-time winner in Montreal, was hoping for a strong result this weekend following a series of races where strong form has been dashed by disappointment.
The German, who had retired from the Monaco Grand Prix two weeks ago because of a problem with his car, failed to reach the end once again on Sunday when a loose hydraulic pipe caused his DRS to stick open.
Brawn was left feeling sorry for Schumacher, who has scored just two points in seven races.
"He suffered a hydraulic issue which left his DRS jammed open and it was not possible to fix it in race conditions," said Brawn after the race. "I can only apologise to Michael for a further technical failure."
Schumacher said there was no use in blaming anyone for the problems that have been affecting him this season.
"Of course it's disappointing for all of us but it's not a question of pointing fingers; stuff like this happens. I know the team are doing their best and that it probably hits them even harder than me. We'll be back on the attack in Valencia."
Team-mate Nico Rosberg finished in sixth position and has now 67 points.