Sorry if I got a little over-sensitive there….
Roger, the model I had was the Adventurer. While I remember that there were several different signals, it has been almost a year since I returned the thing–including the directions–so I can no longer give you chapter and verse. I do know that there were separate signals for "low battery" and for "aborted cycle." I can't remember by now whether one blinked and one didn't or whether they blinked at different rates or what. But there was a definite difference, well-described in the directions. (As mentioned previously, the directions were surprisingly well-written!)
Having decided that the Steripen didn't fit my style anyway, and that with the extra batteries and wide-mouth Nalgene there was no weight savings compared to my ULA Amigo Pro filter, I didn't want to bother hassling with the manufacturer, paying return postage, etc. I just wanted to get rid of it! I had to go to the REI store I bought it from anyway, so I returned it there.
If I were going to take this unreliable (IMHO) gizmo with me, I'd want to bring along enough Micropur or Aquamira as backup to disinfect the water supply for the whole trip. Of course, in that case, why bother with the Steripen? That's actually what we did on the trip I cited. After 24 hours of fussing with the Steripen and trying really hard not to use bad language in front of my grandkids, I stuck the Steripen in the bottom of my pack and switched to Micropur–fortunately we had just enough to get us through the rest of the trip.
I had read beforehand that the batteries drain when left in the Steripen, even when it's turned off, so I removed them between uses. So I don't think that contributed to my problems. But this was another time-consuming fuss-and-bother which should, IMHO, be unnecessary.