How sad you got that frustrated, but I doubt it was the machine's fault.
Janome's are usually fine machines. Threading a serger is always a bit tricky the few times, it is easier. Normally, once threaded, you never thread again, simply cut the thread up high on the machine and tie on the new color or changed thread. also, on a new machine, trial runs with different tensions are necessary to avoid strange stitch patterns. Some stores will give lessons to help you avoid tension clashes, which can be a bother with a serger 'til you get to know them. every change of fabric may need a slight change. Sorry you threw it away, because any sewing machine store will show you how to fix what's wrong if it is a tension, needle, or simply not knowing what to do next.
But sergers need more precise tension settings. there's a 4 dollar threader (loop on a long flexible wire) that once you do that a couple of times, makes threading a snap.