Octoprint Printer Security Warning on Creality CR-10S 300

I'm owning a CR-10S since December 2019. In January I installed Octoprint on a RASPI 3B+.
Connecting it to my Printer brings up a Security Warning where I learned that I have to change the firmware on the printer.
I studied a lot of tutorials and found that flushing the latest Marlin Firmware would be the right solution.
What worries me is that some turorials say I'd first to add a bootloader to the machine others just connect a PC with Arduino IDE and flash it on directly.

Maybe the experts here can help me:
Does a CR-10S 300 from 2018 have a bootloader on board or not?
Can I somehow detect if a bootloader is already there?

Thanks in advance!

I bought my ender 3 pro about a year ago and it didn't had the bootloader.

Well one way is to flash a new firmware via usb.
If it can't connect and flash it then you probably got no bootloader.
But maybe somebody else knows a better way.

Thanks for the quick response.
It's currently my only printer and it prints fine.
So I currently fear to break something by Try&Error.
Let's see if someone else has an idea..