At a descent rate of nearly 1000m/h, brake overheating is likely unless braking is well managed. The energy management in the descent is a skill you will need to learn regardless of improvements you could make to the bike.
'Your gonna need bigger brakes' won't work, you already appear to have fairly big brakes. If you have installed organic pads, change these to sintered (metallic) as sintered handle high heat much better. Better brakes might also help (Stance range is Giants entry level MTBs), they will all overheat if pushed too far.
If you 'hit the gas' between corners, every time you add power (human or electric), this energy has to be removed. This happens from friction and aerodynamics, but an more than these the energy is lost by converting it to heat in the brakes. Don't hit the gas to save a half second between corners.
The next is braking technique - you have two brakes, were you using both? If not, you need to spread the energy (heat) between the front and back brakes.
Were you dragging the brakes? This is bad for heat dissipation, you need to pump them, releasing completely for short intervals provides better cooling. Use aerodynamics to you advantage - make yourself 'big' so the air slows you down.
How heavy are you - a big rider on along descent has to much more careful than a lighter rider as we all get the same sized brakes but the energy that needs to be dissipated is much more for a heavier rider.
Stopping an letting the brakes cool off is always a good option. Better to take a minute or too longer than have brakes fail. Be very careful after stopping to check the brakes before riding off. If really hot, the lack of airflow when stopped means more heat makes it into the calipers and can boil the brake fluid. If this happens, you will have no brakes. This effect has been observed in practice (Usually heavily loaded bikes on long road descents).