There’s a good possibility his brakes did fail, or at least didn’t work properly.
However, he had only been driving for a short time, was coming down I70 without any mountain driving experience or training. Videos showed him going way too fast and missing the runaway ramp.
Whether or not his driver error burned up the brakes, or they malfunctioned, or he was scared his employer would fire him for trashing a truck on the emergency ramp, IMO he could’ve done a couple things after coming out of the foothills.
He drove for about 3 miles on relatively flat ground before plowing into those stopped cars. He could’ve downshifted, coasted, run half on and half off the road to take some speed down. I’m no trucker, but I also understand that most diesel trucks have an engine brake (makes the loud babababbababanba sound).
I think the trucking company should bear some responsibility as well. The kid was clearly not trained or capable for that route.