There's a possibility, SRS module is at fault here. Those first two codes; Power Supply and Internal Control Fault point to SRS module as the problem here and erasing the codes, they will just come back.


The SRS module on E53 X5 is located under the center console towards the back. This exact issue happened to me. I got my SRS module from Ebay. Just make sure you get the exact part number and version.


When you deal with Ebay seller, just make sure he gets you a working module. In my case, it took three modules before I get a working one. The replacement module will have to be programmed depending on the options installed. You can get the list from the old module using BMW scanner and then once the replacement module is installed, program it accordingly.


Goodluck