If your camera began life with an earlier version of firmware, it is a good idea to revert to that firmware before doing the upgrade and to use the appropriate upgrade hack for that version, and not the later hacks. The reason is that at certain points in the Ex series camera life, different hardware and associated firmware configurations were used. My FW 1.19 camera can be upgraded to the latest firmware versions but the hack is best done on the 1.19 and then upgrade to a later firmware, if desired. My 1.19, if upgraded to 3.12 will not necessarily play nicely with the hacks intended for a camera that left the factory with 3.12. There are significant differences in the firmware that loads even though they have the same version number.
You can find out what firmware your camera had when it left the factory by looking at my camera firmware log in my 'E4 Useful information' thread on this forum. Your serial number can be compared to other owners details there and you will see what firmware was used on your serial number.
The E4 Useful information thread is here....
https://www.eevblog.com/forum/thermal-imaging/flir-e4-the-useful-information-thread/For early upgrades, your E5 behaves no different to the upgrade than the E4 of the same firmware.
I just checked. If your camera is HW 1.0, it would have been supplied with firmware 1.19 or earlier. It is the easiest firmware to upgrade as no encryption or othe protection was employed. Only CRC01 to be calculated for the configuration files. This is my favourite firmware as it also contains the full service menu that was removed by FLIR in later firmware versions to prevent its use for hacking. In comparison, firmware 2.3 is heavily bastardised by FLIR in an attempt to stop the upgrade.
The bad news is that Firmware 1.19 was not released as a user installable firmware package. Only 1.18 and countermeasured 1.20 onwards. 1.18 is a stable firmware that has the service menu. You can upgrade the camera running 1.18, plus tweak its menus etc to your liking, and then install a later firmware if you want, but you will lose th Service Menu as a result.
For others reading this response.... do not be tempted to revert to a much earlier firmware than your camera arrived with. As stated, different generations of camera hardware run differing firmwares. The earlier firmwares do not always play nicely with later hardware versions of which they have no 'knowledge'. As a safe option, take a look at my camera firmware vs serial number, and hardware version, list and decide which firmwares were used with your version of hardware. Do not install a firmware that predates your hardware unless you like taking risks with your cameras functionality.
Fraser