You want to check with your realtor about this.
There is no contract if you didn't sign the amendment.
Sounds like you are trying to buy a foreclosure.
If that is the case, chances are if you don't sign the amendment there will be no contract ever.
It will change the buyer friendly contract to a seller friendly contract, but they will likely accept no less.
Of course we are guessing here.....we don't have enough details.