Battery on 2008 Mercedes-Benz C300 4MATIC

Although it sounds obvious its not where is the battery located on a 2008 Mercedes Benz C 300 4 matic the manual says under the hood ... but its not

as you are facing the engine, the battery is located to your left (passenger's side) at the firewall and may be
hidden by a black plastic cover. some have one large battery and some have two batteries. if under 50,000 miles, it is still under factory warranty.
Thanks a million...
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Where is the battery in a 2008 Mercedes Benz c300 4matic?