Hello,
I have the K2 Pro Combo and keep getting the error message BM2355.
Can anyone help me here in the forum?
Best regards,
Stephan
Hello @Elimar2004 
Welcome to the Creality Forum…! 
I don’t know if this helps but the cable to the hot end seems to be a weak link on some of these printers causing the MCU communication error.
I have the K2 Pro Combo and haven’t had that error yet.
Creality has a video here 
K2 Pro Hotend Adapter Cable Replacement
You might not have to replace the cable but the video shows the parts that might need to be checked for looseness.
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Brand new K2 Pro here, will not pass initial setup and calibration with same error BM2355 MCU error.
I just started getting this BM2355 error today and have had some success in solving it by popping off the print head plastic cap/cover and adjusting the thin wires. I straightened out the wiring to point up instead of going at a hard 90 degrees. This post provides some more details. https://www.reddit.com/r/Creality_k2/comments/1nbsouv/i_have_created_a_possible_solution_to_the/
I did not create a physical attachment, I simply pulled the wiring out a little and adjusted them so they were pointing in a vertical direction instead of horizontal direction.