First of all, thank you! Also I found a mistake in my own understanding of the task. I didn't take account that any other letters except 'C' and 'D' lead to absence of additional 20 points. Briefly, we get 20 points if an array consists only of 'A' and 'B'. Unfortunately, i didn't understand it at first.

Print the input to debug your code.

Everything else: 0 points

Your code marks students having any other mark as hacked.

Thanks for the link to the trouble shooting guide. I didn't realise there was a print was unacceptabe on kata.

You don't have any return in your function

Read this: https://docs.codewars.com/training/troubleshooting/#expected-the-same

Not a kata issue. By the way, your code is not 100% right:

After all the calculations, the total score should be capped at 200 points.

Fixed.

Simple issue,

["name2", 140, ["B", "A", "A", "A"]] 
should be
["name2", 110, ["B", "A", "A", "A"]] 

ohh understood thnx

If there are 5 or more courses and all courses has a grade of B or above, additional 20 points are awarded.

Because of that, name4 has a "C".

why name3 got 160 and name3 and name4 has equal length of array and name3 score is getting 20+ extra because of length so why name4 should not?

total += points.get(score) 

That line is in your code, isn't it? Read the error message:

TypeError: unsupported operand type(s) for +=: 'int' and 'NoneType' 

Not a kata issue. Print the input to debug your code.