Check against 2 columns and if true replace value in one

Question

dataframe[(dataframe['Column1']=="Value1") 

and

(dataframe[dataframe['Column2'].str.contains('partial string',case=False)])]='new value to be placed instead'

the above should be looking for 2 conditions... one full match and one partial and if its not in the string, replace with new value

I have used the loc() in combo with str but i keep getting typeerror:string indices must be integers