I would have recognized a runaway trim. Held the electric trim back until I didn't need so much control force. At the same time I'd call for the "Runaway Stab Trim" QRC/QRH. Used to be a memory item.
Both accidents used the trim to stop the motion, but NOT to reverse the trim. Anyone that hand flies the airplane much knows that you have to trim the hell out of Boeings, and trim some more. I suspect some serious training deficiencies, along with lack of experience.
I'm not buying that they could trim manually. They were doing less than 350KIAS. I suspect they didn't pull the handle out to crank it.