Romain Grosjean's miserable Singapore weekend famously culminated in the Frenchman being unable to make the start after his car developed a late brake by wire issue.

It was the icing on a bitter cake for the Haas driver who had endured numerous issues with the updated car - the "worst he has driven in a very, very long time - as well as self-inflicted mistakes including his qualifying crash.

Team boss Guenther Steiner has revealed what went wrong on race day.

"It was strange because in the first corner it worked, but all of the sudden it went away," said the Italian, referring to Grosjean's drive to the grid when the pitlane opened on race day.

"When Romain came back in, all of the electronics personnel tried to reset all of the software settings and it didn't work. The guys then took the bodywork off to see if there was any connector that wasn't connected outside of the gearbox, and there wasn't. So at that stage everyone was quite sure it was the brake-by-wire system, which is inside the gearbox. It takes one-and-a-half hours to take the gearbox off and, at that point, the race would be over.

"It's a system in which the rear of the car adjusts with how much the engine is braking with the ERS and how much the driver is braking with the normal brake," he continued, explaining brake-by-wire. "It is a very complex part of the car, but our problem was very simple. It was a connector that fell off. To get to the connector you have to take the gearbox off and, obviously, there was no time to do that.

"Sunday night after the race, we took the gearbox off and it was as simple as reconnecting it," he admitted. "We'll manufacture a device in Europe to be sent via air freight to Malaysia to ensure the connector doesn't fall off again. It will be fitted on the car before we get on track in Malaysia."

Asked about the updates taken to Singapore, which included a new front wing, floor and brake ducts, he said: "We didn't run the new front wing because the drivers weren't sure how to set the car up with the new wing. We need to re-test it in Malaysia.

"It's very difficult to test something in Singapore due to the walls," he added. "The readings of the data are sometimes different because you get different aero data when you're running between two walls. The brakes ducts all worked. They will be on for the rest of the year with no problem."