Is there any reason why your array is so complex? You have a list containing a tuple containing a list containing several tuples containing lists.....
Anyway, try this (no guarantees, don't have an intepreter atm...you may also need to fix the indents):
def count_char(array, char="a", total=0):
for element in array: #indent-1
array_=False #indent-2. different from "array" above.
for element_ in element:#indent-3
return total+count_chars(element_, char=char, total=total)#indent-4
for element in array:#indent-3
You need to realise that i don't have access to an IDLE now to test this, so you're going to have to figure out the indentation on your own (use your discretion). Another thing, if the code crashes or something like that, you should use your discretion fix it if its a minor bug.
Logically, all it does is check if the array conatins another array. If it does, it checks if that array contains another array...and s on. Finally, when it reaches the last array, it checks if each element in that array is an "a", or whichever other character you may want to search for. This uses recursion...it may be frowned upon if you hand it in for homework, or use it to check large arrays.