it start on ready for just 3 or 4 seconds with (ABS, VSC, and break) after few seconds (3 or 4 seconds) , after that a red triangle with a sound has been appears on the dash screen then the system immediately power off. I had tried that many times Could u please help me to solve this issue
What in it starts? If the engine seems to starts and then shuts down it's actually not starting and is draining the hybrid battery. Stop doing that as the hybrid battery will fail eventually! Put the Prius in ign-on by pressing the power button two times without pressing brake pedal. How many bars does hybrid battery have on mfd? Less than 2? Check the 12V battery voltage you can do that even without the volt meter: Toyota Prius: How to Check the 12v Auxiliary Battery Health - PriusDIY.com just do the Test 1. in step 5. then just power off. If that's bad you may need a new 12V battery or just charge it. If the 12V battery has enough voltage you will just need to read the fault codes. Codes are read in ign-on that you get by pressing the power button two times without pressing brake pedal. You will need a scan tool to read the codes best would be to use Techstream. Cheap way to get it is Mini-VCI. Then you could use it to read the codes and all freeze frame data. If you can post all that here we can surely help.
Ok, so that's not the problem. Most likely you (or somebody else) will just have to read the fault codes and then use them to find what's wrong. We can help once we get the information from codes but first we need the code information.