Python cell Color is not updating in Excel sheet

I want to color the row/column of the excel sheet based upon the result ( Pass / Fail) but unable to do so.

if Data variable is Pass will color Green or else Red,

    def writeData(file,sheetName,rownum,columnno,data):
    redFill = PatternFill(start_color='FFFF0000', end_color='FFFF0000', fill_type='solid')
    workbook = openpyxl.load_workbook(file)
    ws = workbook.active
    #ws[cell(row=rownum,column=columnno)].fill
    sheet = workbook.get_sheet_by_name(sheetName)
    sheet.cell(row=rownum,column=columnno).value = data
    print(rownum,columnno)
    var = str(rownum)
    var1 = "E"+var
    ws['var1'].fill = redFill
    print(redFill)
    print("var1",var1)
    workbook.save(file)

If I am passing the direct Column value as ws['E2'].fill = redFill it's working fine i.e. able to color the excel row/col, but same if passing as ws['var1'].fill = redFill it's not working

what I am doing wrong?

Below is the Output of the code I am running

LoadAmountSlideX 34
LoadInterestSlideX 48
LoadTermSlideX -111
LoanEMI 1,74,984
1
2
3
LoanEMIElement 18,52,690
3 5
<openpyxl.styles.fills.PatternFill object>
Parameters:
patternType='solid', fgColor=<openpyxl.styles.colors.Color object>
Parameters:
rgb='FFFF0000', indexed=None, auto=None, theme=None, tint=0.0, type='rgb', bgColor=<openpyxl.styles.colors.Color object>
Parameters:
rgb='FFFF0000', indexed=None, auto=None, theme=None, tint=0.0, type='rgb'
var1 E3

Process finished with exit code 0