A few times when I played Warzone and me or an ally got boardedand a nade was planted, I’d shoot at the vehicle in hopes of killing the boarder. More than once I got a vehicle assist from an enemy blowing up a teammate, and a few times when I was boarded and a grenade was planted, I survived. Also, if your teammate plants a grenade in an enemy vehicle you can steal the kill by shooting at it. I put two and two together and realised that if you’re boarded and the enemy plants a nade, get your teammate to continuously shoot at your vehicle until it explodes and hopefully he will “steal” the kill, and since there’s no friendly fire your teammate ( who is operating the vehicle ) will survive the planted grenade.
But you can’t damage your ally
For some reason, when you shoot at your teammate when he is boarded, when he blows up, you’ll get a vehicle assist ( pretty sure this only works for scorpions and wraiths ).
Not sure if they fixed this in the update