Toyota Repair: Toyota Sienna Powed Door, rear cargo area, sliding doors

Question
My Sienna 200o slidind door wasnot always working probably.
Reset ECU did not help
I used WD40 to clean / oil and now it is not working at all.

How can I verify if it is the ECU ?
Where is the location of the ECU and how difficult is to replace it do I need to go to dealer or DIY?

Answer
In almost all cases the door control ECU is the problem.
If the van has only one power sliding door the ecu is located on the same side as the sliding door, if it has two power sliding doors the ECUs are located on either side in the very rear and the rear cargo area paneling has to be removed to get to them to replace them.
The level of difficulty to replace the ECU whether left or right is very high.