Mercedes have revealed the exact cause of George Russell's sudden retirement from the Canadian Grand Prix could take "several months" to confirm due to complications.
Russell was leading Kimi Antonelli until a power-unit problem forced him to stop and allowed his Mercedes team-mate to take a fourth consecutive win.
It means Russell trails Antonelli by 43 points in the Drivers' Championship ahead of this weekend's Monaco Grand Prix, live on Your Site F1.
"It was an engine kill that was caused by a failure in the battery, which just suffered a catastrophic failure a third of the way into the race and brought George's race to an end there," said Mercedes technical director James Allison in the .
"We can see enough at the end of the race that the battery was fairly unhappy, some heat damage there, and we'll have to figure out in the coming days and weeks exactly what caused that and put it right."
The new 2026 Formula 1 regulations were expected to cause major unreliability issues across the grid, but Russell's power-unit problem was the first sudden retirement for a driver running towards the sharp end of the race.
There were no signs of the issue and Mercedes deputy team principal Bradley Lord confirmed there was a "reasonable amount of damage" in the aftermath.
Lord added on : "We got the car back and were able to get the module out of it. It had to undergo some unusual safety procedures and then has to be shipped back actually to the UK.
"So it will therefore be several months before the hardware gets back and we need to really dig through the data to understand exactly what went wrong and then work out how we try and prevent a repeat on any of the other modules in the future."
Thursday June 4
12.20pm: F3 Practice
1.55pm: F2 Practice
2.55pm: Drivers' Press Conference
4pm: Paddock Uncut
Friday June 5
10am: F3 Qualifying
12pm: Monaco GP Practice One (session starts at 12.30pm)
2.05pm: F2 Qualifying
3pm: Team Bosses' Press Conference
3.30pm: Monaco GP Practice Two (session starts at 4pm)
5.15pm: The F1 Show
Saturday June 6
9.40am: F3 Sprint
11.15am: Monaco GP Practice Three (session starts at 11.30am)
1.10pm: F2 Sprint
2.15pm: Monaco GP Qualifying build-up
3pm: MONACO GP QUALIFYING*
5pm: Ted's Qualifying Notebook
Sunday June 7
6.50am: F3 Feature Race
8.30am: F2 Feature Race
10.50am: Porsche Supercup
12.30pm: Monaco GP build-up: Grand Prix Sunday*
2pm: THE MONACO GRAND PRIX*
4pm: Monaco GP reaction: Chequered Flag*
5pm: Ted's Notebook
*Also on Your Site Main Event
Watch the Monaco Grand Prix, the first of six races in eight weeks, live on Your Site F1 this weekend.
