The movie and your picture make it clear. Rover 1 was made inoperable by the same sand storm that almost killed and stranded Mark.
In the book, both Rovers are fine. The official screenplay also implies it. The movie straight out changes it. For background in the book, screenplay & movie, during the storm, Watney is suggesting to anchor the MAV with the guy-lines of the Solar Farm/Comm Mast tied to the Rovers. In mid sentence, he gets smashed by flying debris.
Later, in his science the shit out of this speech, the screenplay and movie differ:
But here’s the rub. I’ve got two rovers designed to go a max distance of 35 kilometers before they need to be recharged at the Hab. That’s problem A.
Okay, so here's the rub. I've got one working Rover designed to go a max distance of 35 kilometers before the battery has to be recharged at the Hab. That's Problem A.
Both feature the same scavenging of Rover 1, as does the book.
While the Book goes out of its way to point out that both Rovers were designed to take a beating in a sand storm, the screenplay is vague about Rover 1's condition, and the movie shows us how beat up it was.
Rover 1, which is identical to Rover 2, is clearly smashed in, half buried and sticking up in the air. At Least one of it's 6 wheels have fallen off!
Triple A doesn't provide service on Mars yet.
For reference, Book, Chapter 2:
Both rovers are half-buried in sand, but they’re in good shape otherwise. Their pressure seals are intact. Makes sense. Operating procedure when a storm hits is to stop motion and wait for the storm to pass. They’re made to stand up to punishment. I’ll be able to dig them out with a day or so of work.