Could I have damaged the abs control unit while changing the brakes?

I changed both rear discs and pads, the rear right abs sensor was disconnected and has now been reconnected and the fault light dissapeared from the dash.

But I now have both Electromechanical power steering and traction control engine lights showing on the dash. Apparently these can be the result of a disconnected battery which I did remove overnight to change. 

But the car did feel a bit unstable after changing the brakes, I put this down to new pads breaking in and it has indeed got a lot better, I'd probably say up to 95% after a short amount of driving but why are these fault lights still on?

How can I check or test?