Powequery Formula using If inside other ifs

Yes, and it is easier. In Excel it is IF(Condition, True, False) and you nest other statemetns in the FALSE section.

In Power Query it is always 3 statements, it is either:
if then else if
or
if then else

if [some field] = 1 then "It works"
else if [Some field] = 2 then "It doesn't work" 
else if [some field] = null then "It is empty"
else null

You must have that final else. It isn't like Excel where if you omit the FALSE condition it still works. It will throw an error in Power Query.

And it is case sensitive. if/then/else, not If/Then/Else, or IF/THEN/ELSE. Those will throw errors.

The issue is you cannot reference cells in Power Query, so there is no AS6 or AZ4. 

You need to share data with us and explain what you are trying to do. It may be PQ isn't the right place for it, could be a DAX measure. Could be a combination. 

Never approach a Power BI project with "how do I translate this long Excel formula into Power BI?" It is always "How can I create this output in Power BI with this data?"

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