Hi,
Today I use the controller and the left stick was not smooth in the vertical movement (throttle) .
At both ends , it has the trend to return a litle back and at the lower end it makes a loud  "click" like something is jammed inside .
I have it only 3 months . If I open it and try to fix it , will this end the warranty ?

Any suggestions ?

Hello there Man0s. I am sorry for the trouble this has caused and thank you for reaching out. Since this issue is happening on your DJI remote controller. I would recommend you contact our support team at https://www.dji.com/support?site=brandsite&from=nav for further assistance. We will do their best to find out the reason of the issue and then the corresponding resolution would be provided. Just a reminder that  DJI do not recommend doing a DIY in fixing the said DJI drone to avoid further damaging the said unit. Thank you.