Yes it’s safe as long as you have the vehicle hooked up to a running vehicle to maintain 13+ Volts in the charging system/battery voltage. Also ensure the data is backed up first in advanced mode. Then be sure the internet wifi is strong and go ahead, anything less than this and the cas 3+ is a brick. Just takes the voltage to drop below 12v in the flash coding and you are toast. It’s pretty easy to ensure success, just don’t be lazy and skip the jumper pack or booster cables to a running vehicle. Good luck!