I have had my sienna at toyota 11 times for the same problem either the left or right power door fails and will not respond to command and either will not open electrically or close. they replaced the door motor the door computers and they still fail but not at the same time. the mechanic at toyota told me the computers that control the doors are bad to begin any suggestions to fix the dual powers doors for good? Toyota does have a TFR (trouble and failure report system) and their is one I discovered on this issued and toyota did replace the computers at their expense one time when they warantee expired but will not do it again
This won’t fix your problem, but if they are a constant hassle, disconnect the power door motors and use them manually.
There has to be a positive cure , so I would suggest you look up a different tech/shop.
Do NOT tell them who you previously went to and what they said.
Let the new shop come to their own conclusions.