QUOTE(minglibing @ Jun 7 2016, 11:54 AM)
I think I might have identified the source of the problem - my USB car charger. It really does fast charging, even with an iPhone 6 plus and note 4 at the same time.
But I think it malfunctioned either because it got too hot or because of a faulty iPhone cable (known for their low quality original cables, but I digress), because I remember smelling a slight hint of plastic burning in the car last week but couldn't identify where it came from. Immediately after that I realized that the iPhone cable was no longer working. Then we could hear a very soft but high pitched buzzing sound, which stopped when the car charger was removed. The next day onwards, I continued to use the car charger with no problems, and a couple of days later the iStop sign kept blinking and the warning sign was lit.
I've not plugged in the car charger since yesterday afternoon, and the iStop sign has since stopped blinking and warning sign no longer comes on

So I went to Mazda @ Glenmarie, and it was indeed the battery problem. My car is 1 year old and 28k mileage, and I was told that the iStop blinking+warning sign lighting up was an indication of a weak battery.
According to them, turning off iStop will extend the life of the battery. First battery replacement is free (took 2 hours).
On a side note, I highly recommend the main centre in Glenmarie, because service is very friendly and good, and there is a lot of comfortable places to wait and work with laptop. They even walked to the cafeteria where I was sitting to inform me that my car was ready.
My experience with other service centres are as follows:
PJ branch: Very crowded and uncomfortable waiting area and takes ages to service car. But staff very friendly and helpful - I wanted to top up cash for fully synthetic but they told me that fully synthetic not so suitable for m3.
Bangsar branch: Very laid back, feels like a small town outlet, and somewhat dishonest (refuse to return excess oil from service even when I asked for it). Also my mileage was 21k+ when I sent in for service and they wrote 30k for next service. Tried to sell me fully synthetic for m3. Not friendly at all. But took only 45 mins to service car. So I don't know if I should listen to Bangsar or PJ
Glenmarie (the second centre further down from the main one): Some staff very malas. Some ok. Again, villager-level urgency. Car ready also don't inform - saw my car outside and asked them about it only say oh your car is ready. And they honestly were not that busy during that time. But of course when their superior come out suddenly very friendly and efficient la.
This post has been edited by minglibing: Jun 10 2016, 12:06 PM