head unit

hi guys i have had my mk1 fabia vrs for less than 2 weeks and after 2 days of ownership the airbag warning light came on this was the day after i fitted my sony head unit, could this just be coinsidence or could the radio of caused it.

the car is now back at the dealers and is waiting for a new airbag ecu it brought up the code 65535

any help would be appreciated, i put the standard head unit back in just in case, i hope its coinsidence as im wanting to upgrade my ice as soon as i get it back

thanks phil