Husky 1542 oil drain valve won’t operate

[fruitcakesa]

Attempting to drain the oil from this new to me mower I found that the plastic “bolt “ that opens the valve won’t move. When I put a screw driver in it and try to open it, the soft plastic just deforms. Same thing if I use a hex wrench. The manual says push and turn the entire valve CC but it seems to be solidly tightened.
Any advice? Thanks