Fired in 1 day

I am a nurse from Israel, worked for Legacy from october 2006 at med/surg (it was most medical)and today I just had a conversation with a safety/quality manager and was given an choice to quit myself or... she was going to fire me. This came as a result of 2 incident reports when I was rotated to serg unit ( 1 of them was the delay of surgery,- which I "did not report Low K level...a month ago the other report I was not shown at all, I was explained that I did not follow the protocol , did not sign here, there, and that it is UNSAFE for the patients , whom I take care of

I have a question Do all new grads really come to the unit with the knowlage of all protocols and procedures? I am not sure that next time some other protocol will not be new to me
What can I do to avoid such things? Is it OK in States to fire a person in 1 day and not to SHOW the report on him?

Thanks
Svetas