I have this problem too, though it began after I had had the printer for 2 weeks.
I've replaced the EE-SX671 sensor on the Z-axis upright with the spare, just in case, also checked the voltage on the sensor board on the print head is within the operating range (1.55v-1.70v), which it is.
Cables checked. Firmware updated.
As with previous poster soggy29797, the LED on the sensor board flickers when you switch on the printer but no longer reacts to any pressure on the print head (LED never lights up). The print head is just driven straight into the bed until you switch off the machine.
I got a 'please be patient' email a week ago but today I have now been told via an automated email to install 'Creality Cloud' that will 'solve all your printer problems'...!
I pretty sure that the problem is the strain gauge and/or the sensor board but, I can't get an human being to actually converse with me about it to arrange a replacement.
Come on Creality, you are seriously dropping the customer service ball here.
I'm a first-time 3D printer buyer and bought the CR-6 SE on the back of it's supposed novice-user friendliness.
This situation is not filling me with confidence, waiting months for the printer to arrive only to break after 2 weeks.
It's not been a great introduction to the world of 3D printing...