A throttle is of no use when the engines can't respond to it. The engines (3 out of 4) initially did not respond to the pull-back from takeoff power at around 1500 feet. The pilot then pulled back to flight idle, and the engines dropped to flight idle. Unfortunately they then did not respond to the throttle back up, and remained stuck at flight idle. You can't keep a plane in the air with 3 out of 4 engines at idle for very long at 1500 feet. (You also can't fly a plane very well with the engines stuck at TO power, they aren't going to last all that long and it's a bit hard to land that way.)
The engine controllers are called FADEC (Full Authority Digital Engine Control) for a reason. Controlling a modern turbofan or turboprop engine isn't like squirting gas into great-granddad's Hudson flathead, it's just a little more complicated and it takes a dedicated controller to keep the engine running optimally.
I don't know what "missing files" exactly means in this instance, but I bet the controller software gets updated to include a validation check on the calibration tables.