Thanks to all for the advice. I removed the inner panel and felt around for the manual release but found none. I then went to the pick and pull to practice on their cars. No wagons but a couple of sedans. I found the plunger and was able to operate it with my finger. But when I got home, I found that the wagon is different. The solenoid is way less accessible. So I popped the door open with a padded screw driver, since I was told the little plastic piece that holds the door shut costs less than a dollar. If is does, I'll bet that's the only piece in inventory that cheap.

I plan to remove the solenoid and lubricate the plunger to see if I can get it working.

Thanks again for your help.