Then it's likely there is a miswire or poor / no connection in your wiring, and you will need to trace it out and test it all.
If it is only the brake light wiring that was altered, it's unlikely a miswire would destroy things, if it's the usual "12v" lighting, but if it's battery voltage or there is other wiring involved, there is some wiring on these things that when miswired can damage or destroy things.
So before fixing any miswires if you find any, make sure you note what was connected to what, so you will be able to tell what might have been damaged or destroyed (otherwise you will have to guess).