Hi all, first of all sorry for the long post but I had to somehow explain the issue. In short: I am calibrating the kitty and once I can go through "6.1.2. Upload and run WriteInstinct.ino " , servos move and everything looks ok. Now in 6.2 I should use WriteInstinct.ino in order to send "c" command in order to enter the calibration mode. Now with the *.ino file "c" command is ignored. Only thing what I bet is one beep and no servo moves. Longer explanation: I think these is an inconsistency in the calibration process or part missing. On the main Calibration page https://docs.petoi.com/chapter6 it is written that "n previous sections, we have prepared those body parts, but haven’t screwed them onto servos. If we don’t calibrate the servos before attaching them, they may rotate to any direction, get stuck, and cause damage to either the servos or body parts." - so parts are not screwed or mounted to prevent damage. Then we go on through the calibration process part 1 on the web page "6.1. Write constants" which moves servos and performs other calibration and after we finish that we should do chapter "6.2 Enter Calibration mode" https://docs.petoi.com/chapter6#6-2-enter-calibration-mode . There it is mentioned "You MUST plug in all the servos and battery for proper calibration. Then in the serial monitor, type ‘c’ to enter calibration mode. The servos should rotate one by one with unnoticeable time intervals then stop. Depending on their initial shaft direction, some may travel larger angles until stopping at the middle point. There will be noise coming from the gear system of the servos. You will see the calibration table:" - so to me this still looks the same parts are still not mounted . In the Forum post https://www.petoi.com/forum/basic-assembly-and-setup/i-can-t-finish-calibration-and-first-move Rongzhong Li answers: "In writeInstinct.ino, it just writes constants to the static memory. Token “c” will make the robot stand on elbows and knees. “kbalance” makes it stand on feet. You may have some mistakes when attaching the legs during calibration. Enter “c” first then attach the legs in 90 degrees. After uploading Nybble.ino, the cat will self balance when stands up. There’s a voltage watcher that beeps if the voltage drops too much during movement. Since you are powering the servos directly by the batteries, it’s probably the limited discharging ability of batteries." so the questions are: Do I have to mount legs now after chapter 6.1? How to enter the mode where I can execute "c" ? is "c" for Calibration or for kitty to stand up? do I have to upload Nybble.ino to enter "c" calibration process or not? Thanks for your help.