First download latest firmware from Ubiquiti download page, then execute the following command on UniFi Cloud Key via SSH:
ubnt-systool fwupdate https://dl.ubnt.com/unifi/cloudkey/firmware/UCK/UCK.mtk7623.v0.13.10.e171d89.190327.1752.bin
First download latest firmware from Ubiquiti download page, then execute the following command on UniFi Cloud Key via SSH:
ubnt-systool fwupdate https://dl.ubnt.com/unifi/cloudkey/firmware/UCK/UCK.mtk7623.v0.13.10.e171d89.190327.1752.bin