Based off Marlin 2.0.8 (bugfix)
If you are getting great prints from your Kobra PLUS keep in mind that you can't fix something that's not broken. Updating your firmware may void your warranty and may or may not perform exactly as you expect it to. Thus, firmware updates are at your own risk.
You will be using a host via USB to complete the firmware update (Repetier Server Pro, Octoprint, Pronterface, etc) if you are using the AnyCubic stock firmware. If you are updating from a prior release of mine release only re-flashing the firmware is needed. I.e. don't do the M502/M500 from a host.
The firmware here was designed to work with Anycubic's original Tri-Gorilla_ProA V1.0.4 motherboard and a Nextion LCD that uses a DWIN_FOLDER. Anycubic has changed their production run so new Kobra Plus's with a Tri-Gorilla_ProB V1.0.2. There have been reports of the original firmware not working on the newer production or replacement motherboards. To determine which motherboard you have, the original uses a USB type B, the newer motherboards use a micro USB connector. The photo shows the difference.
The animation graphic will appear on the LCD, within 10 seconds you will hear five beeps from the printer and the LCD will display the main menu. NOTE The printer may hang during this update, power down, wait 10 seconds and repeat with power up (it can take two or three times to work)
----- only contnue if updating from the AnyCubic factory stock firmware -----
[Pronterface Download] (https://github.com/kliment/Printrun/releases/tag/printrun-2.0.0rc8)
If you want the M117 support, use the DWIN_SET, place that on a black SD card, with the printer power off, insert the card in the LCD SD card slot, power up, updating will require approximately 25 seconds. A success message will appear the top of the display. Power off, wait 10 seconds, power on.
Be aware the DWIN_SET is a very colourful display set, not the monochrome look of the stock LCD.
eSteps for extrusion, any PID tuning may have to be redone
CJ = Classic Jerk LA = Linear Advance JD = Junction Deviation
After considerable testing with Linear Advance, this is disabled. The 30% extra printing time when it was enabled wasn't offset near enough by the minimal quality increase.
When the printer receives the M600 filament change GCODE:
Note after purging there is a slight delay before the hot end returns to the print job. Be patient.