Get a lawyer if your firing was unjust. As for Manitoba PNP, your employer has to support your nomination so I am guessing they would not have supported your application anyways. The employer has to offer you long term employment. You must find an employer will to support your nomination and then work full time for 6 months.
To apply to the Skilled Worker in Manitoba (SWM) Pathway, you must demonstrate ongoing Manitoba employment as your established connection to Manitoba.
Ongoing Manitoba employment means that you possess a valid work permit and a Manitoba company has offered you a full-time, long-term job after you have completed at least six months (continuous) full-time employment with that company as a temporary foreign worker or international student working graduate.