On the nRF52DK builds there is no bootloader, so it won't do OTA at all (even with a zip). It's a complete pain to get working and requires an encryption key and two separate builds (one bootloader, one firmware), so for a devboard I just skip it :)
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
I just copy the hex onto the JLINK USB drive.
On the nRF52DK builds there is no bootloader, so it won't do OTA at all (even with a zip). It's a complete pain to get working and requires an encryption key and two separate builds (one bootloader, one firmware), so for a devboard I just skip it :)