I had the same problem with a complete new setup Q500+ with case batteries etc. The lights were doing the same thing and not charging. I emailed Yuneec in Germany, I even phoned them to chase it up. Said they would send me a label to send the charger on to them. A week later and after chasing and trying to buy a new charger from them - they sent a label attached to an email. I didn't know what I was supposed to do with it, so I phoned them and asked what to do with the package - they said I would have to find a DPD agent and take it to them - I asked where to nearest one was to me - they said go onto the internet and find it - charming customer relations. So I did this - traveled a round trip of thirty miles and sent it off. Again after chasing it up they said they got it and it will be returned repaired and the repair was only a fuse and I should have checked it and replaced it myself. As has been said - the lights were blinking and as it was new - I didn't imagine the fuse was faulty.
It was returned to me and my brother (who was visiting) got it when I was away - he also got a Q500 4k which had been to Germany for repair at the same time and was addressed to me, but should have gone to Italy. When I found this and sent them an email about it - they sent me an email with details attached. This time a DPD van would pick it up at an agreed date from 0800 to 1800 - they didn't turn up that day or the day after. So fed up with the hassle, I said I would take to the DPD agent if they sent an email label again. Who would have thought that a little fuse would cause so much hassle. (and they say DJI is crap at customer relations)