Dead 12 volt.

the easy way is applying 12v to the jump point under the hood, either from another vehicle, jump pack, or other 12v source.
the hard way is to use the mechanical key in the fob to open the drivers door (if it is locked) then open the rear door, tilt the rear seat back down and climb into the hatch with a small screwdriver and flashlight.
there is a small panel by the hatch lock with a mechanical lever to open it. you have to push up and out to lift the hatch door, it helps to have someone outside lifting it.

 

+1 on what @bisco said.

There should be a detailed write up on jump starting, and on how to manually open the rear hatch in the owners manual. If the vehicle doesn't have a set of manuals, you can download them here : Toyota Warranty & Toyota Manuals | Toyota Owners

Opening from the inside involves removing the rear plastic deck, the storage tray, and a small plastic cover, then you can push the level to pop the rear hatch while pushing up at the same time.

 

It’s physically difficult if your older.

Go buy a jump pack there pretty cheap now and hook it to the front jump point like bisco said.

 

OR ask around of friends and neighbors for one you can borrow.
If it starts up and seems to run OK with a jump, you should have already scouted out a shop to drive it TO to have a new battery installed.

The new battery needs to be fully charged.......sometimes they are NOT.......and the charging voltage should be checked too.

 

I am not able to post a new question: My 12 v engine start engine dies numerous times, Had it tested numerous times. if I play the radio or leave a door open, or charge the phone the battery dies and has to be jump started. Is there a way to put in a regular size larger size 12V battery which usually is very less costly than a prius 12 volt battery?

 

NO, not a "good" way.
You need to:
Get the charging voltage checked while the car is running (ready).
Those activities that you listed should NOT run the battery down unless several hours are passing.
If you leave it is "ready" mode while doing those things, it shouldn't run the battery down but the engine will run occasionally.

IF your battery is more than 5 years old, just replace it......and be sure the new one is fully charged.
Every time it requires a jump, it needs to be fully recharged with an external charger.
The onboard system in the car takes a LONG time to do that, if ever.