Seatbelt & airbag warning lights after Dynamat install

[Fuzzzy]

I just picked my Z up from the local audio shop after having Dynamat installed.

The good news: on my 12-mile drive home, it sounded much improved. I think I am going to be very happy with it.

The bad news: after I got close to home I noticed that the seatbelt warning light in the tach was flashing and that the passenger airbag warning light near the glove box was illuminated. But both windows appear to function properly.

I searched this forum and found several threads about resetting the airbag light if it is flashing. Mine does not flash; it just comes on and stays on. I was going to try the re-set procedure anyway, but it is difficult since the first step is to wait for the first time it flashes

I found only one thread about that seatbelt light flashing which suggested that it was probably not connected properly.

I strongly suspect that the wires were not properly reconnected, but I have no idea where to check and probably could not do that (yeah, I know) even if I did.

Is this likely the source of both issues, or is there something else I should check out prior to going back to the audio shop Monday morning?