You may have a faulty GFCI...test it and again with a known good appliance.

If the GFCI holds, then you have a ground fault in the pressure cooker. Either disassemble the cooker to the electrics and fix the short or return the cooker under warranty.
Chances are you can even get a replacement outside of warranty if you talk nice to the company.
Google it and get the company website.
If you bought it from bed bath and beyond just return it, hopefully with the receipt.