I was using my pi 3 with the official power supply and compatibleenter image description here keyboard and mouse. I was just using geany like I normally would when the lightning bolt appeared (the sign for overloading the pi) and then the screen turned blank. Now it won't boot and the red light shows. I have another pi which I have put the sd card Into and the card still works. Any ideas on how to resolve?


  • The lightning bolt symbol is an indication that you're under-powering your Pi, rather than overpowering it. See: here.
    – goobering
    Apr 24 '17 at 11:53
  • @goobering I said overloading. I.e there wasn't enough power to run which is also underpowering. Apr 24 '17 at 11:59
  • No need to act like that. It is probably a power problem, that resulted in the Pi shutting off.
    – Dr_Bunsen
    Apr 24 '17 at 14:25
  • @Dr_Bunsen I have tried different power supplies and sd cards and also other peripherals since this and the pi just will not boot. Also I didn't intend to come across as aggressive. Apr 24 '17 at 14:28
  • Did you short the pi? Or damage it by under powering it? I read something about that being a source of damage.
    – Dr_Bunsen
    Apr 24 '17 at 15:24

it probably is a power supply problem.

The allowed voltage range is the normal one (for 5V logic) 5.0V ±5% so its a the range between 4.75V and 5.25V. Note that the lower limit of 4.75V is more a matter of many USB devices not working below that value than it is that the PI itself is that sensitive, especially as much of it (including the ethernet/hub chip, and the SD-card) is working from 3,3V through a regulator on board of the PI that will keep working even with say 4.0V.

Also note that many 5V logic devices will be damaged by voltages of 6.5V or higher! Therefore there is a protection device on the PI (D17) that will short the 5V supply if about 6.0V is supplied! Then the (poly)fuse will blow out to protect D17 from burning up! If you do not power the PI through the normal micro-USB port then you are actually bypassing that fuse!

there is a section of the PI Wiki at http://elinux.org/RaspberryPiBoard dedicated to boot problems like this.

  • Ok so my poly fuse has probably just blown Apr 24 '17 at 10:20
  • @that_raspberry_pi_guy But why would that situation have arisen on your Pi?
    – joan
    Apr 24 '17 at 11:24
  • @joan I don't know. My cpu temperatures escalated and then it just showed the power supply overload. I wondered if there was an error in the cpu that drew a lot of power and got very hot. Now it is not doing anything but thankfully my sd card is unharmed Apr 24 '17 at 11:27
  • 2
    The red led is part of the 3.3V system and so could not be on if the polyfuse were blown raspberrypi.org/documentation/hardware/raspberrypi/schematics/… <- The fuse ("MF-MSMF250/X") is top left, the leds are in the second row on the right.
    – goldilocks
    Apr 24 '17 at 13:04
  • @goldilocks ok, so this points away from the cause being a short? Apr 24 '17 at 15:30

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