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I'm in need of some explanation as my Pi is acting weird (to my limited knowledge at least)

It will only boot when i suply it with 5v/GND through the 3.3/GND GPIOs.

  • The pi boots when i connect 5v to the 3.3v pin (with only the yellow led blinking, nothing on the red, and gives the little thunder icon on its raspbian desktop)

  • It boots normally with the expected behavior on both leds (and no thunder icon) when i connect both the micro usb charger and the second power supply to the 3.3v+GND.

  • Tried two different micro usb power supplies alone, nothing, they only light the red led (no yellow led blinking). Tried 5v+gnd (from a 16x relay board) to the 5v+GND, nothing.

  • The 5v power i am connecting is from this Powered 16x Relay board (stack exchange link)

  • It's a relatively new setup (a month old) and it's been working ok till today that i disconnected the power from the relay module to reboot it.

Have i fried something?
I imagined the micro USB might be damaged, but how would that explain the fact that i need to power it through the 3.3 and not the 5v?
How can i make it boot with just its official power supply again?

krasatos
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    Probably. The Foundation says "Under no circumstances should a power source be connected to the 3.3V pins". See [Raspberry Pi Power Limitations](http://raspberrypi.stackexchange.com/questions/51615/raspberry-pi-power-limitations) – Milliways Apr 21 '17 at 02:54
  • @Milliways is the module supposed to act as a powersource? is it normal that its pins read out 5v? Check the link i provided on me asking how to connect the 16relay module. It was the only way to get it to work. – krasatos Apr 21 '17 at 07:43
  • It is not feasible to check all the hardware and the link does not point to any module. You stated "The pi boots when i connect 5v to the 3.3v pin" and "suply it with 5v/GND through the 3.3/GND". I suggest you disconnect **everything** to make sure your Pi works, **DO NOT** connect power to **ANYTHING** except the USB power port. If you have already asked a question, you should modify the original. I was only responding to this question. – Milliways Apr 21 '17 at 08:47
  • Thanks for your reply @Milliways, Check the 3rd bullet on my question: When i connect ONLY usb, i get just red led on and no boot – krasatos Apr 21 '17 at 08:51
  • In this case your Pi is probably dead! There are other possibilities, blown polyfuse (try in 24 hours) or SD Card problems. – Milliways Apr 21 '17 at 08:54
  • @Milliways but it does boot if i connect power to the 3.3v pins. How can it be dead? This also rules out SD card problems + Blown polyfuse is supposed to not give any led indication at all, according to rPi forums boot troubleshooter (" If the fuse has blown no power will reach the PI, meaning the power LED will be off! ") here: https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=58151 – krasatos Apr 21 '17 at 09:04
  • If you supply __3.3V__ only to the 3.3V pins and the RPi boots then you have a damaged/blown power supply part that converts the incoming 4.5-5.25 V on the power (micro-USB) connector down to the 3,3V (and lower voltages) that the RPi core and SD card uses however other bits that use the 5V rail - not sure off-hand what those are - will not be working. That being the case your RPi is crippled rather than dead but returning it to a healthy state is not likely to be within the average (or even skilled) users' skill set - so you may have to face that it is a write-off and bound for the ⛼ ... – SlySven Jul 11 '17 at 15:44
  • The weird thing is that in order to start it up, i need to jumpstart it by shorting the Pi's 5v to the Pi's 3.3v for an instant. Then it boots up and runs normally. Unfortunatelly that leaves me with a non-operating pi in the case of a temporary power black out. It wont boot up on its own. It works normally, all the rails and pins have the correct voltage once it is running. – krasatos Jul 11 '17 at 20:00

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