Finished

Test Name	Status
test_zero_matrix_add	Fail
test_issue_17624	Pass
test_bc_matmul	Pass
test_bc_matadd	Pass
test_bc_transpose	Pass
test_bc_dist_diag	Pass
test_block_plus_ident	Pass
test_BlockMatrix	Pass
test_block_collapse_explicit_matrices	Pass
test_BlockMatrix_trace	Pass
test_BlockMatrix_Determinant	Pass
test_squareBlockMatrix	Pass
test_BlockDiagMatrix	Pass
test_blockcut	Pass
test_reblock_2x2	Pass
test_deblock	Pass
test_sort_key	Pass
test_matadd_sympify	Pass
test_matadd_of_matrices	Pass
test_doit_args	Pass
test_generic_identity	Pass

     def _blockmul(self, other):
         if (isinstance(other, BlockMatrix) and
                 self.colblocksizes == other.rowblocksizes):
+            return BlockMatrix(self.blocks*other.blocks)
+            # Multiply the blocks
+            result_blocks = self.blocks * other.blocks
+            # Convert Zero scalars back to ZeroMatrix objects with appropriate dimensions
+            from sympy.core.numbers import Zero
+            # Create a new matrix with proper ZeroMatrix objects for zero blocks
+            # We need to determine the correct dimensions for each block position
+            def _convert_zero_to_matrix(element, i, j):
+                # Convert Zero objects to appropriate ZeroMatrix
+                if isinstance(element, Zero):
+                    # For block (i,j), the result should have dimensions:
+                    # rows: self.rowblocksizes[i], cols: other.colblocksizes[j]
+                    return ZeroMatrix(self.rowblocksizes[i], other.colblocksizes[j])
+                return element
+            # Apply the conversion to all elements in the result matrix
+            from sympy.matrices import Matrix
+            converted_data = [
+                [_convert_zero_to_matrix(result_blocks[i, j], i, j)
+                 for j in range(result_blocks.shape[1])]
+                for i in range(result_blocks.shape[0])
+            ]
+            return BlockMatrix(converted_data)
         return self * other

uv