Car Does nothing after hooking jumper cables backwards

Hey Gregory L. Jackson,

First thing to do will be to check all of the fuses. Guide below.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

By connecting the two batteries in series you have effectively doubled the battery voltage.

This will cause all consumers to try and draw twice the current that they normally would.

You need to check all of the regular and mini fuses along with the large power supply fuses.

Work your way through all of these first.

If your battery is dead, replace it.

Try again and see what you get.

You may have done some damage to the control units in the vehicle but the first step is to get rid of that battery and replace any fuses that are blown.

Regards, Joe

Thank you Joe, I'll try, but everything I look up says I probably destroyed some relay's and/or control module when I hooked the jumper cables on backwards. Please help. Used module? It is a 2007 Mercedes Benz E350. I don't want to spend more on repairs then the car is worth. Thank you for your reply. Sincerely, Gregory

Joe, one more thing I forgot to add on the 2007 Mercedes Benz E350: Ever since I hooked up the jumper cables wrong (reverse positive cable on negative post), the car won't do anything: The key won't turn in the ignition, the car won't recognize the key, the windows are down and won't roll up, the sunroof is open and won't close, no horn, no nothing. I know I fried the battery, so I had someone jump me correctly: The trunk lights came on, but that was all. Nothing, including the key doesn't work, nothing works. Everything I read says I most likely ruined come type of control module. I don't want to spend more on the car then it is worth. Help please! Used module? Any suggestions? Thank you for your reply. Gregory

Hey Gregory L. Jackson,

As i said before, before jumping to control unit replacement you need to replace that battery and check and replace any blown fuses.

Let me know what you have after doing this.

Regards, Joe