Gerald: I have 2 BBBs that will give a single brief flash of the power LED 
when the power button is pushed, as described by others. It will not 
sustain the power LED on nor boot up. When I power it from the barrel 
connector (Adafruit regulated 5v power source / AC to DC 5v 2A) while on a 
digital volt / ammeter, no current flow registers at all during the brief 
flash of the power LED. The voltage reads 5.08 volts. I cannot see that 
this is due to either an unregulated power source (also happens on USB 
power on 2 PCs by the way). Nor does it look like excessive current draw. 
Other ideas?

On Thursday, June 11, 2015 at 9:08:39 PM UTC-4, Gerald wrote:
>
> The flashing LED indicates excess current is being drawn by the processor. 
> This can be related to damaged I/O pins or power supplies that are not well 
> regulated..
>
> Gerald
>
>
> On Thu, Jun 11, 2015 at 4:38 PM, <[email protected] <javascript:>> wrote:
>
>> I have the same issue, already 3 boards has died.
>> any solution, i tried to use optoisolator/pwm and noting. the BBB is a 
>> bad board.
>>
>>
>>
>> Le mercredi 25 février 2015 18:03:24 UTC+1, [email protected] a écrit :
>>>
>>> Identical problem this morning:  BBB boots fine when powered by USB, but 
>>> not when powered by a 2.0 mA rated 5.0 V DC power supply (nicked from some 
>>> other device).  BBB power LED blinks continuously.  This power supply has 
>>> worked with this BBB in the past.
>>>
>>> Mike.
>>>
>>> On Friday, January 23, 2015 at 8:44:59 PM UTC-8, [email protected] 
>>> wrote:
>>>>
>>>> I had a similar problem- my power LED would just continue blinking when 
>>>> connected to a 5V power source. This meant there was something wrong. 
>>>> First, I checked if my BBB was still alive. To find that, I connected my 
>>>> board to a computer via USB. Surprisingly, this time power LED  turned on 
>>>> normally. Then to make sure that everything was properly, I ran some 
>>>> program as given in the BB website 
>>>> http://beagleboard.org/getting-started.  I was happy to see, the 
>>>> programs on the website worked just fine on my board. Thus, I was able to 
>>>> conclude that strangely, my BBB board didn't like 5V external power source!
>>>>
>>>> On Friday, November 22, 2013 at 6:41:41 AM UTC-8, Bert Lindner wrote:
>>>>>
>>>>>
>>>>> Just had a 5V powered Beaglebone Black seemingly die on me. First the 
>>>>> power led kept blinking, then after removing the (BB Toys CAN) cape the 
>>>>> power led would flash just once after applying power. Looking back in 
>>>>> previous threads this seemed to mean I killed the board somehow; there 
>>>>> was 
>>>>> also a GPS module attached to one of the UARTs and a probably power 
>>>>> hungry 
>>>>> USB wlan stick that I'm trying to get to work, so a power hungry setup.
>>>>>
>>>>> I was ready to declare it dead, it remained just flashing once after 
>>>>> repeatedly unplugging and reattaching the power supply.
>>>>>
>>>>> However I noticed the single power led flash would also happen if I 
>>>>> pressed the power button (leaving the 5V plug in). Doing that repeatedly 
>>>>> seems to have revived the board, will see if new problems occur. For now 
>>>>> it 
>>>>> behaves normally.
>>>>>
>>>>> Is this expected behaviour?
>>>>>
>>>>> Best,
>>>>>
>>>>> -Bert
>>>>>
>>>>>  -- 
>> For more options, visit http://beagleboard.org/discuss
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>
>
>
> -- 
> Gerald
>  
> [email protected] <javascript:>
> http://beagleboard.org/
>  

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