my 2002 ml500 wont start after replacing water pump

First check your battery voltage or try jump starting. Look over all your work and make sure you didn't forget to plug in a connector. Also, if you have another key try that too. If nothing works then you will have to scan for codes to see what's going on. If you prefer to bring it to a shop, use this link to find a good one near you. https://repairpal.com/repair-shops Alex