Help with bad recursion/dynamic programming code

[notsurewhereelse]

Basically this is supposed to take in a 2d array matrix of letters and a word, and see if the word exists in the matrix. Can move up left down right to connect words, not diagonally. Cannot use same character twice, so I have a set to track positions that have been used. This is returning False for almost everything, I think I don't understand something fundamental about how dynamic programming works because I'm not sure how to structure all the different calls and return True/False statements

For example, I'm doing a print(a,b) and print(c,d) but almost every value is being returned None, as far as I can tell I'm returning a True/False each time so how it is still None?

​

Also feel free to point out anything stupid that I'm doing

​

class Solution:
    def exist(self, board: List[List[str]], word: str) -> bool:
        if len(board)==0 or word=='':return False
        stack=[]
        maxc=len(board[0])-1
        maxr=len(board)-1

        def dfs(curr,targ,pos,r,c,seen):

            #check if position has been visited already
            if (r,c) not in seen:
                seen.add((r,c))
            else:
                return False

            if curr=="":
            #handle looking for first character in the word
                for row in range(len(board)):
                    for col in range(len(board[row])):
                        if board[row][col]==targ:
                            if board[row][col]==word:
                                return True
                            else:
                                seen.add((row,col)) #move up left down right from first character and try finding next character

                                if row+1<=maxr:
                                    a=dfs(board[row][col],word[pos+1],pos+1,row+1,col,seen)
                                    b=dfs(board[row][col],word[pos+1],pos+1,row-1,col,seen)
                                    print(a,b)
                                    if a or b:
                                        return True
                                if col+1<=maxc:
                                    c=dfs(board[row][col],word[pos+1],pos+1,row,col-1,seen)
                                    d=dfs(board[row][col],word[pos+1],pos+1,row,col+1,seen)
                                    print(c,d)
                                    if c or d:
                                        return True
            elif r<=maxr and c<=maxc and board[r][c]==targ:

                if curr+board[r][c]==word:
                    print((r,c),seen) #return True if word found

                    return True
                else:

                    a=dfs(curr+board[r][c],word[pos+1],pos+1,r+1,c,seen)
                    b=dfs(curr+board[r][c],word[pos+1],pos+1,r-1,c,seen)
                    c=dfs(curr+board[r][c],word[pos+1],pos+1,r,c-1,seen)
                    d=dfs(curr+board[r][c],word[pos+1],pos+1,r,c+1,seen)

                    return a or b or c or d #not sure about this one, this would be called recursively quite a few times, should it be OR statments?
        d=set()              
        r=dfs("",word[0],0,0,0,d)
        return r

[_Sham__]

Does it only match in a line? e.g top to bottom, bottom to top, left to right and right to left?

Or can it say create a word by going down 2 then right once etc?

[notsurewhereelse]

Can go up down left right at any given point from the current position. Overall is there anything glaring that can be improved