Abs Trac off and misfire

[Franksdad]

Hey guysiI know it has been a while, so I was going to bring my car into theshop for rear brakes and a ccylinder six misfire, simply because I am working two jobs and have no time. My little brother offered to do them for a hundred bucks so today he only changed one set of brakes and switch out a coil pack, he brought my car back with a misfire and abs light and Trac control light. Can this be caused by just doing one side of the brakes?? Or any idea what could have went wrong? And Imean cconsideringiI'm only misfiring on six it's clearly either a plug or a wire right? I have no idea why he bought a coil now I'm going to be working on the car tomorrow any input is greatly appreciated because I'm panicked and about to hurt my little brother lol