Great to hear that your problem seems to be an easily cured one. Looks like you bought a nice little bargain!
Steep learning curves? Yup, I'm an "oldie" too and much happier hitting things with big hammers or chiseling with a chipped screwdriver! Like you, I've also been "fiddling about" with wee Fiats for many years and find myself challenged by all this electronic gear. About 3 years ago I bought a fully licensed version of
Multiecuscan from Gendan (very helpful people who have happily continued to give ongoing support). It is an ongoing learning experience for me - and there is a great depth of knowledge available through the good people on this forum - but when I look back to what I knew a few years ago compared to now, I've managed to climb up quite a few rungs of the "ladder of knowledge".
I bought the Multiplexed interface because I wanted the convenience it affords but the multi lead adaptors would seem to work just as well - you just have to connect with the right leads for the controllers you wish to communicate with (you get on screen prompts.) I have read reports that some of the cheap interfaces don't work very well and some require modification before they will work properly. So if, like me, you are not all that savvy in these matters, Buying from an approved seller - Gendan being just one - is probably the best option.
When you buy your licence is for one year. (that was how it worked when I bought mine) so during that year you can download updates for free. After that time expires you must pay to download new versions but the installed version will continue to work just fine. I've so far found that my 3.8 version (latest one is 4.5) does everything I want on our 2010 Panda and 2012 Punto so haven't found it necessary to update.
Here's some links you might like to view:
https://www.multiecuscan.net/
https://www.gendan.co.uk/category_174.html
https://www.youtube.com/watch?v=N1D4Hk2r6xk&t=39s
If you're going to continue messing about with Fiats you really need to get into
MES Especially on the diesels where you need it to reset the computer after oil changes so the DPF regen thing works properly and, of course, for service rests which you can't using the dash buttons (as i can on the VAG stuff).
Good luck with it all and welcome to our community
Jock