Sometimes a bad sensor will disable the ecu , so when you replace it , it will still not recognize, I would use ISTA+ to fix this, you might get lucky an due able to unhook the battery and get it to come back up, or maybe use a scanner like a AUTEL to re calibrate it, all that being said you could have bigger issues like a ECU swap, I had this on my e60 after the swap .
I bought this car recently, the oil level sensor is only inactive, I changed it, I tested it with one of a friend and nothing.
I wanted you to help me to solve this problem.
Sometimes a bad sensor will disable the ecu , so when you replace it , it will still not recognize, I would use ISTA+ to fix this, you might get lucky an due able to unhook the battery and get it to come back up, or maybe use a scanner like a AUTEL to re calibrate it, all that being said you could have bigger issues like a ECU swap, I had this on my e60 after the swap .