Power door is not delatching

It is not clear whether your key fob continues to work for the passenger side door. If it does not, you should replace the battery in the fob. Such batteries are available at Wal-Mart among the batteries. If the sliding door on the driver's side makes a noise but fails to open when you use the fob, the latch motor maiy have failed. If the cable in the side door has frayed and snapped, this would explain why you can manually open and close the door but the electronics won't move the door. And if while trying to close it manually, the door fails to latch properly, this is why you get an alarm. If the latch motor, cables, or any other components are malfunctioning, it could lead to the door not closing securely, triggering the alarm. Check your latch mechanism and cables. If you can determine the malfunctioning part and replace it yourself, that is cheaper than going through the dealer. Here is a service manual: https://www.manualslib.com/manual/1061909/Toyota-Sienna-2004.html

What To Do When Your Sienna's Side Door Won't Open Or Close ' Toyota Parts Center (olathetoyota.com)

Try changing batteries in Key Fob

the noise you can hear is the lock/opening actuater, have to strip out door panel and see if the actuater mechanism is intact, and operate as before and look to see what part is trying to move, it may just need lubricating but be prepared to have to have new lock actuator

Is it locked

Try this... it fixed my problem whereby the 2005 Toyota Sienna passenger sliding door would sometimes open and sometimes not, yet I could hear the motor trying to open/close it. It cost me 20 minutes and 10 drops of oil, not $1200.

First, get the door open. It took me two weeks of constant trying, but it finally opened.

Next, remove the plastic covering of the inside door handle this way: locate the two screws on the forward edge of the sliding door near the child-safety switch: (the switch is a small lever near the door latch, on the forward edge of the door) loosen and remove the two phillips screws, one above the child-safety latch, and one below.

Remove the plastic cover to expose the gears for the door open/close mechanism.

There's a bunch of intricate plastic and metal parts in there, all coated with white grease. I used some 3-n-1 oil to lubricate everything in there thoroughly, In my case, there was one part that was a little void of grease, hence it "stuck" occasionally.

Test the system. If it's Okay, replace the plastic cover, and re-install the screws.

Now my Toyota Sienna 2005 door never fails to open or close.

Check out the wiring. Sounds like something is loose or the switch may be going bad.

This may or may not work depending on exactly what is wrong with the door, I cant tell what is wrong without looking at it directly however:
You can try starting with all doors closed and unlocked, keys in hand disconnecting the battery and letting the vehicle sit for 2 min or so, then reconnect the battery. Put the key into the ignition and turn it to the on position but do not start the van. Next press the button to disable the power sliding door for the drivers side, then manually open the door fully, wait 5 seconds, then close it manually fully. Press button the button again to re-enable the power sliding door, then try to use it with the automatic feature either by pulling the handle or using your remote, this may or may not work depending on if the door has somehow become de-initialized (it should work now) however if something is broken inside the door closing mechanism or door closed/open sensors, the door will continue to malfunction.

motor or switch.. its cable driven people used to cut cable and make it a manuel door due to cost... check that ck to make sure mater switch is not powered off as well

The suggested fix above did fix my problem. The problem is that a 2.5" hinged finger that pops up from the floor of the door opening to block the door. Apparently, the finger should, but doesnt go back down after the gas flap is closed. Even after I got hinged finger down (so that the sliding door would open/close all the way), it still would not go back down after the gas flap has been opened. i.e. I have to push the finger back down every time after we fill up with gas. It looks like there is a little wire/spring that should pull the finger back down, but it is off of the finger. I think that replacing this back on the finger should fix the problem permanently.

the sienna has a latch type which is interferring the door use a screw driver and tap it down then the door will slide then next oil change have them lube it