My take by now as far as voting fraud concern is that, during Trump first four years in WH, he most likely couldn’t penetrate with his allies either FBI or CIA. Penetrate maybe a too big word for it, control is more realistic. Hence, no real power in defrauding the whole voting system with the mules, machines, software etc. Moreso, remember in 2019 there were reports in a press including our gracious host JPF on shenanigans involved glitches in a voting machine with leads to Spain, Germany and other countries. Most of these machines are a particular brand (I forgot the name), and they are purchased by most of the countries with democratic systems. I guess it is a part of Bushis plan of "spreading democracy " for the rest of the world American style. 
Trump was not allowed to do anything about it because the same machines that controlled election in USA, also control election throughout the world.