The FX3 can definitely overheat, especially when shooting longer clips at higher resolutions/bitrates. I've had it overheat and shut down on me a few times when shooting 4K 60p indoors. Proper cooling is essential. I use an aluminum camera cage with a fan mounted to keep it running for longer periods. An external battery grip can also help by reducing heat from the internal battery.

Overheating has been one of my biggest frustrations with the FX3 so far. Even with just modest ambient temperatures, it will overheat fairly quickly, especially if using it in the default video mode. Recording externally to an Atomos monitor definitely helps extend recording times. Have also had decent luck leaving it in power saving mode and avoiding 4K 60p when possible.

use ice to cool down 😎