Over the past few weeks we have noticed an uptick in the number of bricked Twiddler3's being reported. It's still a very small number of units that are affected but, to those users it is a big problem. So, we have been working on finding out what is going on. The issue involves writing to the flash and power.
When the Twiddler3 writes to Flash, it needs power to be present at all times. If power is lost during a flash write process, the chances of it corrupting the flash are extremely high. Given the topology of the Twiddler, the odds of this happening are extremely low. That is until recently...
We make everything for the Twiddler in batches - PCBs have their own batch cycles, Plastics have their own batch cycles, Batteries have their own batch cycles, even the packaging has its own batch cycles.These cycles give us the opportunity to trap and isolate an issue with certainty.
Over the last few weeks we have noticed that some of the power switches from the last batch of Twiddlers are performing less than optimally. By that we mean that the switch performs its function of turning the power off and on, but it also can do so without a directed intention to do so. Slight pressure around the case near the switch or a pinky graze over the switch can cause it to momentarily cycle power.
So, when you plug your Twiddler into USB on a MAC, the OS likes to write a hidden file to the Twiddler. If you have one of these sensitive switches AND you grazed, tapped, or applied indirect pressure to it while plugging it in and it cycled power, chances are you bricked it. If you use other OS's on your host, you are not immune to the issue, the events that could cause the issue just happen less frequently. This is why most people think it is a twiddler.cfg issue as that is one of the only times when flash is being written. Most of the time it is only being read.
There was a lot of variability in tracking down this issue as everyone uses their Twiddlers differently. Not only different from person to person but in handling it from day to day.
If your Twiddler was delivered with 13B & 14B firmware, there is a small chance of having one of these switches installed. (Issue rates are less that 0.1%) If you have not noticed an issue yet, there is a very good chance that you do not have a switch with an issue. If, at any time, you do have an issue, open a support ticket here: https://www.tekgear.com/contact/ and we will work on getting you back up and running right away.
For those of you with X-ray eyes, the switches are batch code marked 6F & 7B. Not all 6Fs and 7Bs have this issue, only a small few.
Keep in mind that the power switch should always be left in the ON position. Let the Twiddler's time out function do the power down. The power switch should only be used when you ship the unit and if you store it for a long time.
tldr; We've found out why some Twiddlers are being bricked. It's a switch problem. Power cycle during a flash write can corrupt the code space rendering the Twiddler inoperable. Send unit back to unbrick it.