I don't know if is possible to downgrade a vci, maybe, but try re-writing it again with the latest firmware released, current one. make sure you either have the correct power supply to it or if is connected to the car, good battery voltage. there is always the risk of software corruption or hardware damage when rewriting a firmware to anything, vci or ecus, the reason it is only done when directed to do so. keep this in mind for future references. hope you get it fix. check the FAQ section, there could be something related to your issue or do a forum search, good luck.