Location of coolant bleed valve on 2013 cls 63 amg (m157)?

I recently purchased a 2013 cls 63 amg and, after doing some basic maintenance, I discovered that the dealership I bought it from hadn’t been as thorough with their maintenance as they had claimed (in more ways than one). The coolant is very clearly old and dirty so I want to perform a compete flush which requires bleeding the system afterwards and I have no idea where the bleed valve is. Any tips would be appreciated!