2017 300C with a V6 won't start but will start with a jump start

It seems that there is a drain on the battery. The car is under warranty, take it to the dealer and let them find out what is wrong.

Intermittent issues can be a pain to track. Have to test when problem is ongoing. Make sure battery has a full charge and battery connections all good. With digital multimeter across battery posts, have a helper crank it, if it will crank, what is the voltage reading? Generally it shouldn't drop below 9 volts, some makes and models say 10 volts, you get the picture. When problem is ongoing, don't use jumper cables and do some testing. I realize if your headed to work or an appointment, you don't have time to fool with it. I understand. If it cranks good but won't start, check for spark at the plugs, engine cranking. Also check proper fuel pressure and fuel injector pulse. Any applicable trouble codes? Engine cranking all vehicle systems get battery voltage. Engine running, all the systems get generator voltage, that can be several volt difference. You may have a voltage drop problem, somewhere?

Just check the battery voltage and it was reading 12.5Vokts. Tried to start and car WONT START. The battery then drops to 10.5 Volts. Just read the engine code and it is P1DF3 just not sure what is causibg this error code. Will give a jump start and car will run like normal unles you ahut it off then the car goes back to NOT STARTING

Weak battery.

Did you get a resolution same car same issue here

same issue