My 2006 Prius engine not turned on

Plug a suitably capable scan tool into the car and read the trouble codes, and post those here so we know what your car is complaining about. Then we should have some suggestions for what might need fixing.

Using the techniques on this page, you can get some of the trouble codes without needing a scan tool:

Blink (a/k/a Flash) Codes – How to. | PriusChat

However, that method will not show you the codes that are behind the warning triangle being on, and those codes are likely to be the most informative ones.

 

It won't go into Drive? If yes, and you don't have the scan tool, first charge your 12V battery and see if it will go into drive.

Edit: I saw no trace of OPs reply when I posted. Odd. Maybe I just missed it somehow among the ads.

 

Use your cheap scan tool clear the codes back to back TWice now will the car go in gear,? ? If so when it codes again you'll have to clear the codes again twice to get it back in gear. You got accumulator problems with the brake and apparently low voltage issues with the 12 volt battery

 

Check the voltage of the 12v battery.

 

For at least 5 years I’ve been using an ad blocker, both on pc and phone, mostly motivated by this site.

 

Looks an awful lot like a P0AA6.................but a 0AA6 usually lights up the dash prior to shutting the car off, then won't let you go READY again, unless it's really bad...... Did you get these lights while you were driving, then shut the car off and now can't restart it?

The 1241 code isn't likely to be the culprit for not going READY.
Now, if you have a bad connection on the 12v, and are intermittently losing 12v power to the car, you may just need to press the power button 2x with your foot on the brake. Does the auto up/down work on your driver window? Did you lose the radio station presets?

Sooo many questions to learn the circumstances prior to "My 2006 Prius engine can't turn on. All warning lights are on."
Those answers can often lead to better ideas.

Since the code scanner probably isn't picking up hybrid codes anyway, you can always just go ahead and disconnect the 12v battery for a few minutes. Measure the voltage on it for fun to see what it's at. If it measures bad, charge it or replace it. If it measures good, disconnecting it should reset all the ecu codes, so reconnect it and see if you're able to go to READY again. It will take 2 pushes of the power button (foot on brake) to make it go ready after disconnecting 12v power.