Thank you for the replies gentlemen!
I just bought the car used and there is no remaining warranty and no extra smart key or flat key. He only had the one key left. I did replace the two small batteries in the key itself and am going to order an extra key to see if that resolves the problem. Otherwise I'll look into the EIS.
Thanks again for taking the time to reply as I know people are very busy and this board moves quite fast these days! It is greatly appreciated!
01 S55 AMG Silver
01 CLK55 AMG Silver