Adding my reply to the original post to this thread as well:
Hi all. Sadly we have now experienced this as well Even worse, it happened while we were demoing our product overseas However, the reason I really wanted to post is that we may be able to add an important bit of information: Our battery was charged. It was probably around 60-70% charged. However, our product has this button on its exterior that we use to hard power off the unit:
That button breaks the ground connection to the battery (battery becomes open circuit when OFF). We were demonstrating this, ie using our on/off button. We turned our product on and everything worked fine, we turned it back off and then when we went to turn the unit back on again we got the blue light of death. So in our case I am pretty sure it wasn't from a battery drain, but from the on/off cycle. Now, there is one complication to this: before re-powering after our last successful power-on our external case was opened. This should not have made any difference at all and is unlikely to have contributed to the failure, but it is a change that happened right before the failure so I have to report it.
[EDIT] Ug, I should also mention that solar panels were also connected to the Vin/GND pins, but the unit was inside so minimal I/V was coming in through these.
Mod edit (@harrisonhjones): Merged two posts (see EDIT for second post content)