Misleading shift/job description - Avis employé Inventory Associate Hörmann

I was assured there was no mandatory overtime. I was very particular about this during interviews as I cannot work weekends. Within 3 weeks, they told me it was now mandatory to "help out" on the floor running machines and weekends were now mandatory. When I reminded them that I could not work weekends, they said it looked bad since I was still in my probation period and I was refusing to do my job. They tried to get me to sign a paper stating that I was refusing to do my job - I had to quit or be fired. They still have not sent my final paycheck.