Version5.0.0
Electra One firmware
Version 5.0.0 is the current firmware. From 5.0.0 on, firmware is not published on this site: the files are in the Electra One app, on the Update firmware tab, beside the online update.
the 5.0.0 firmware, in the app
What the update does on the controller, and what to do if one goes wrong, is described in Firmware update for the mk2 and in Firmware update for the Mini.
Running 4.1.4?
Version 4.1.4 and everything that goes with it - the firmware for the Mini, the mk2 and the mkI, the SD card images and the recovery files - is in the documentation for that version:
The version is chosen on the front page, and every page of the documentation says which version it belongs to.