I had my Mercedes GLA45 flash tuned for month no issued, recently it let me read but when I write back "write calibration" message pop up "write fail to erase". Lucky for me car still running. My battery hook to charger and try 2 different labtop with no luck, I used the lasted beta as Tech support suggest. Tech support still working on it so far no solution yet. How can I get back to stock firmware? I appreciate for any input.