Most likely the belt broke. 30 YO rubber belt will tend to be dried out, maybe a bit sticky so when it's started up for the first time in maybe decades, might work for half a minute then just fall apart.
You'd need to search the forum but supposedly there are stocks of replacements that can be gotten for most models.
If you have one of those car cassette adaptors with the aux plug then you could use an MP3 player to play audio recordings of Atari tapes to load games.
I saw earlier this year that someone was selling belt sets. I'll look it up. Thanks.