If the carpets have been wet in the past for any reason then the impact sensors
could be the problem, but to look at them you need to remove the seats and the lower seatbelt mounting bolt to enable the carpet to be peeled back.
Yours will be the green ones on the left in Artic's picture above, if the metal backing is covered in white corrosion then it's likely to have got water ingress and suspect. Markypicks one was exactly like this
In a worse case scenario it could also be the SRS ECU or the power supply to it
Russ