If they engage when power is applied that seems to be a sign that they were calibrated in the wrong order. The order the ESCs are laid out on the board doesn't match the way they are laid out on the UI for the calibration page. I did them in the wrong order yesterday on an ROV and had the same problem. You want to make sure when you do your 2nd ESC you are actually selecting the third option on the calibration UI. Let me know if that works! Watching which motor is twitching when you enter calibration mode on it can help too.
You should not have to move the sliders from 0 to keep the motors still.
The motors match to the ESC's as follows:
||Pads on 2.5 circuit board
As far as nothing working(no beep or flash) that happened yesterday as well on the pink ROV and we just turned off all ESCs, unplugged the home plug adapter's USB cable, and restarted. Then everything worked ok.