Battery in my Sienna was dead one morning, no real reason. Jumped it and sent my wife on her way with the jump box. Alternator tested out fine at about 14v. Did a full charge on the battery later that day. Since that time, at random, the power doors (two sliding doors and rear hatch) refuse to work. Would this be related to the battery? Van starting up just fine and no other real issues.

 

Maybe a fuse is blown

 

Sienna`s have had various electrical issues for awhile, My sister family has 2 of them with the power sliding doors opening on their own , non starts and then just by turning the key off and back on it does start. Google Toyota Sienna electrical issue. Not one of Toyotas better vehicles.

 

I think letting the battery go dead really screws up these modern cars - as opposed to just disconnecting a fully charged battery from the car.

Check to see if maybe there's some sort of reset procedure for the sliders. I know that some cars, including my 2005 Mustang GT have a reset procedure for the power windows. I did it on my car, and got the windows to start dropping an inch when the door is opened, and raising back up once it's closed. I had to do each window separately, and then they all worked. But another funny thing happened - my airbag light which had been stuck on, went off, and now only comes on for a few seconds when you start the car, like it's supposed to.

So you can see that the mass computerization of these modern cars can cause all kinds of problems - but can sometimes be fixed with a simple systems reset.

And the window reset procedure is to open the window and keep the button depressed for two seconds after the window is all the way down. Then simply close the window within 30 seconds or whatever, and again keep the button depressed for two seconds after the window is all the way up, and that's it! You'll probably have to do each window. I'm not sure if the Sienna has reset-able windows, but some other system might.

Check the google or the owner's manual.