I'm not very familiar with hydraulic slides. Here's a link to an operating manual for hydraulic slides by Lippert. There's a trouble-shooting section on pg 11.
The good news: I got it opened by running the generator and then sliding it out. Apparently, the batteries were not charged enough to supply enough power to turn the motor. The battery gauge showed 3 of 4 lights lit.
The bad news: The carpet under the couch ( when slide is retracted) was wet along the edge of the slide. I sure am glad we decided to buy a new unit so we wouldn't have problems like this!