BMW E90 Facelift 4 cylinder 318i built in 12/2011 Problems with indicators since repair?

Beautiful good day,

I have a question regarding a problem with a friend's car. I replaced the valve cover gasket 2-3 weeks ago. Everything worked fine, but I made a stupid mistake at the beginning.

I wanted to disconnect the positive wire at the point marked in blue, as shown in the image above (this is a photo from the internet, not my friend's car), so that an unwanted electrical circuit would not be completed. However, I did not disconnect the battery in the trunk beforehand (yes, I know, if I had done that, I would not have had to disconnect the positive connection). Of course, I then slipped, touched the engine, completed an electrical circuit and caused an arcing. I abruptly pulled my hand away, then disconnected the battery and continued changing the seal.

After I returned my friend's car, he contacted me shortly afterward and said that his turn signal was now flashing very quickly. It was as if, for example, a turn signal light was broken. However, the hazard lights were working normally. I then disconnected the battery to reboot the system. The turn signal flashed normally for a short time, but after five seconds, it started flashing faster again.

I looked online to see if I could find anything. I read there that it might have affected the control unit under the seat. That's what I feared, too, and I hope I'm wrong. It said that the onboard light monitoring could be coded out to prevent the problem from occurring again. Another forum mentioned that the turn signal lever might be defective. Unfortunately, I don't have a BMW tester to check for any of the errors.

Maybe someone has had a similar problem and can help me. The car otherwise works perfectly and has no other issues. Thanks in advance, and have a nice day, stay safe 🙂

Kind regards, Marko