More info, this is what Autel Maxysys report after trying to Proxy allignement:

You could try unplugging the airbag ECU (disconnect battery first!) and then try the Proxi again. However when you reconnect the airbag ECU (disconnect battery first!) you will have to do a Proxi again which may fail. I have followed your instructions and I have not been able to do the alignment. W...

Sorry for the delay in replying, I had the car in the upholsterer this week. It is original and also I have tried with another unit with the same reference and I also have the problem, with both it does the same. This is the log u mean? 09/05/2021 18:42:04 Fiat 500 1.2 8V Siemens Airbag MY06 (Ep - P...

Good morning. I had a problem with a 2008 Fiat 500, 1.2 8V. The car had a problem in the electrical installation and due to repeated short circuits the sw of the body computer was corrupted. Bad checksum. The recalculation was made and the sw was repaired and after repairing the electrical fault eve...