Did you resolve the problem?
I have similar problem. 2014 GD 1.4 petrol I30. Hyundai service located the problem: electric power steering do not shut down when ignition is off. Problem is solution they propose, to change complete EPS system, around EUR 1.300. I’m looking for cheaper solution, to locate the cause of the problem and replace the component that makes the problem.
When I turn off the motor steering wheel is still easy to move and MDPS ECU is warm on touch. When negative pole of the battery is detached steering wheel stiffs and MDPS ECU cools down. I have achieved the same effect by detaching and attaching power connector on the MDPS ECU (it is easy reachable under the steering wheel). I reckon that MDPS ECU is problem.