2004~2008 Mom's '07 airbag module

So....I've been gone quite a while. Sold my '02 Protege5 six years ago. In retrospect, not the smartest thing I've ever done, but that's not why I'm back here today.

My mother happens to have a 2007 Mazda3. Been a great reliable car for her since she bought it new (at my suggestion), and that's important to me since I live 170 miles away and can't effectively keep track of her automotive maintenance needs as much as I'd like.

I wish I could hold her local Mazda dealer in such high regard. They are always trying to sell her a bunch of BS "recommended maintenance".

Anyway, her airbag light recently came on, so she took it to the dealer for diagnosis. Charged her $100 and told her she needed a new SAS module, to the tune of $499.

She declined in order to give me the opportunity to get a second opinion.

So here I am.

Thoughts? Is this an easy DIY repair?