Why would my abs light, brake light, and trac light be on after getting brakes replaced?

I brought my 2002 Volvo s60 to a repair shop to have new tires, and a front end alignment done. After bringing it to the shop, they told me that I would also need new brakes. So I proceeded to get those fixed as well. Paid 700 dollars in total for all the repairs, and got my car back on the road. Three days after having it on the road the ABS light came on, the brake light came on, trac light came on. As well as a message on the side of my car saying “brake failure please stop safely.” I haven’t even had my car back for a week and this happens. I drove my car well over 30 miles like this, and the brake system was fine. Stopping short was no problem. I’ve never had any problems with the computer system in my car before this happened. After bringing it to the mechanic they told me that it will most likely need a new ABS module which can be up to 700 dollars. The mechanic is in no way admitting to the fact that he did something wrong, and isn’t paying for this problem. What is the coincidence that all of these lights would appear? I’m assuming they wouldn’t have if I didn’t get the brakes fixed.