Valve actuator stopped working

Hi,

I have a solar heating system with my in-ground pool. Pentair SunTouch controller and Pentair CVA-24 valve actuator to divert water to solar panels. Everything was working okay till last weekend. But this morning I noticed that the valve didn't move even though the controller says "solar", and thus water was not diverted to the panels.

This is fairly new system that was installed 2 years ago.

1. What are the first things that I should check?

2. Is there some switch or anything in the actuator so that I can manually turn the valve and heat the pool until the problem is solved?

Thanks.