"...no one has nailed down precisely what happened between protesters and government troops..." That, @scmp, is not true. Here's a cable from the British Foreign Office that gives a fairly exact description of what happened - the best bit's below.
https://en.m.wikisource.org/wiki/UK_cable_on_Tiananmen_Square_Massacre?utm_source=share&utm_medium=ios_app&utm_name=ios_share_flow_optimization&utm_term=control_1 …pic.twitter.com/Ow2yLGG64r