Please note that the T4 Kaleid (T4K), Kaleid, and Kaleid flux and are different controllers, and have different firmware.
Warning!!! Do not install the wrong firmware, as installing the incorrect firmware will likely brick your controller, and installing any of these firmwares on a T4 Kaleid (T4K) will render it unusable and unrecoverable.

Kaleid Flux upgrade steps:

1.Press and hold LOGO+Menu while connecting  the cable to a computer. 

Click here to watch the instruction video for Kaleid flux

Click here  to download the update file for Kaleid flux

2. Open the upgrader and Click “Download” to upgrade.

3. The progress bar showing “Upgrade SUCCESS” indicates that the upgrade is completed. Users can now open the GameSir Nexus app to set the polling rate to 1000Hz.

After upgrading the controller firmware successfully, you can turn to GameSir Nexus to toggle polling rate.

P.S.: While using the 1000Hz Polling Rate, the earphone and native trigger vibration functions will temporarily be disabled.