The flashing tip means either that the battery was on for longer than the cutoff point (typically 5 to 10 seconds) ... or it needs to be charged.
Other than that, I have more questions than answers.
Is this an automatic battery (i.e., no button on the side to press)? Auto
batteries notoriously activate when stimulated, not only by sucking on the e-cig, but also by sound and movement.
Did this cost about $10 or so and come in a box with gold Q on it? That's a "disposable" with a short-life battery (but which should be able to be recharged a few times). And don't judge the Vapy Award-winning "Joye 510" by it.
How many puffs did you and your friends take on it before it died? It sounds like it was ten or twenty or so. "The guy" said it was "a bit charged." Even fully charged, the 510 battery needs to be recharged quite frequently.
Have you tried charging it yourself for a couple hours?
You know, the more I contemplate what you have described, the more I realize that you haven't given the use of e-cigs an iota of thought. Frankly, I'm not sure that
vaping is for you.
Don't hesitate to prove me wrong by researching this wonderful world of
vaping. Speaking of which, you could start by browsing that the illustrated guide of that name linked in my signature. Then PM me to tell me how off-base I was. [I'd love to hear from you, but doubt that I will.]