you probably have a failing abs sensor which is the key part in the systems. You said you lowered the car so the shock had to be removed yes you could have damaged a sensor doing so or not reconnected or refitted them securely, but the other could be tyres with different tread depths or sizes from left to right on the front and back of the car causing the sensors to read different speeds at the corners also cocking the wheel in the air normally at the back in the bends normally on track, hitting deep puddles/ pot hole with one wheel can bring and ABS fault which resets on restarting the car. Low brake fluid level can bring on handbrake light you need to tell us how you removed the shocks did you lower the sub frame or compress the springs and pull the shock from the hub assembly. I've just looked at the last post you say on track it's the problem a Clio cup racer could explain but they normally use the Renault clip to disable the esp. and abs functions as hitting the track kerbs hard can fool the abs and esp systems cutting power at the same time. If the steering has been disconnected when dropping the sub frame and the wheel is turned when disconnected then it needs the angle sensor zeroed as steering angle is used for traction and esp.
There are so many people that jump in with their problems it's hard to answer the original problem, to tell you the truth if you buy a Renault clip they are great for diagnostics if used correctly I bought one for £125 it goes into more depth than a £20 eBay job as it costs say £35 to £50 for a dealer to plug in every time and with an intermittent fault you need it there and then. On my 172 Clio it was able to tell me which of the 2 lambdas was faulty and that it was the internal heating element which gave random emission lights and limp modes while the £20 gave a basic error code relating to emissions.
