HI all,

it takes a long time (12sec) to switch from playback to record, have this problem since today

Hi there, please use a TB50 battery and install it on the DJI Ronin 4D, keep it off and leave it for 10 minutes, turn it on and check if the issue is the same.
If the issue happens every time you switch it from playback to record, you are recommended to send the Ronin 4D back to us for further check.
If needed, please click https://www.dji.com/service/repair to start an online repair case.

id did what you said, IT WORKS !!!!!  THANK YOU !!!!!