2001 S80 2.9

My SRS light and warning message came on randomly one day after my car stalled at a stop light - it's not a normal occurrence, but it happened that day. After I cut the car off and cranked it again, the light came on. Not knowing any better, I disconnected the battery for 24 hours when I got home but now know that won't reset it.

So today, I took the car to a mechanic to troubleshoot. He hooked it up to their scan tool, but the tool couldn't communicate with the SRS computer. (I don't think the tool was unable to because it wasn't compatible, but rather the SRS computer was shorted or something.)(By the way, this was at a military base and their scan tool is one of the huge dealership-type ones....)

Where do I start with troubleshooting/replacement? Since the tool couldn't communicate, do I start with replacing the SRS module and go from there?

Of course, I'm trying to keep from taking it to the stealership, so any advice/direction would be appreciated!

Edit - OK, looks like the diagnostic machine pulled two codes but I forgot what they were (I'll get them Monday) but both were for Air Bag Module.