Originally Posted by n10cities

Correct, you MUST perform the TX/RX calibration on page 8 of the SRS4210 receiver manual BEFORE attempting ESC calibration. Here is the link to the manual:

https://www.spektrumrc.com/ProdInfo/..._Manual_EN.pdf

You must do this whether using AVC or not. If you are NOT using AVC, you must use two bind plugs: one in the BIND port, the other in the DISABLE port. After performing the TX/RX calibration, the standard ESC calibration will work normally. Fought this one all day trying to calibrate a Mamba Max Pro with this rx and a Spektrum DX4C.