Rasberry pi 3b+ not working power issues

My rasberry pi 3b+ shows different responses to different ways i powered it it worked for the first couple of days and now is acting weird powering it via the micro usb the area near the usb gets extremely hot and the pi shows 3.4V using a multimeter (i no longer have it borrowed it off of neighbour) going through the system and i can not plug any usb devices into it otherwise it enters a boot loop. powering it via the gpio 5v and Ground the ones that are next to each other the pi will not turn on indicating gpio pin failure and but if i put the ground to the other at the bottom it boots with red power led but no activity led unlike when it was powered via the micro usb. the area near the usb still gets hot i thought it was the polyfuse and left it for a few days still got the same result and now the 5v pins at the top of the gpio pin layout no longer give any response when i use the multimeter. i would like some assistence i don’t have any pictures as of yet but if you want some i will upload them but i will not be able to show any multimeter measurements i will also reply late as i have work all day and no mobile internet (i hate prepaid).

the gpio power setup is a 12v (used to power a fan active cooling) psu brick that has been stepped down to 5v (for the pi) through a dc to dc buck converter and has been preconfigured to run 5.1v before i plugged it into the pi it worked with another one i had before this but that showed no activity regardless of what method i used to plug it in or what os i was running and that turned out to be a factory defect this is a new pi i got from that warrenty. power spikes also i don’t think was the issue as the voltage stays even when a multi meter is put on it.

look fowared to hearing what you have to say
regards Jesse.

Hi Jesse,

Thanks for sharing those details. It’s fair to say that something external to the RPi is at fault, as we have replaced it with a brand new (and tested) RPi.

If it were me, I’d do some load testing on the buck converter, and also inspect the voltage rail for noise.

Bear in mind also, most of the GPIO pins are hard wired directly to the BCM chip. Any misconfigurations on GPIO can cause permanent damage.

I hope you can find the cause of the issue; we won’t be able to send you a third replacement Raspberry Pi board given the moving parts and non-official hardware being used with this RPi though.

i have check for noise and and load tested it and it is adjustable it is not a non adjustable buck converter so i am not sure if it would be that plus if the gpio pins were hard wired directly to the chip why would the fuse be acting up and resisting voltage that is what is confusing me plus it still works is the main thing if i did fry the pi completely then it would have not booted at all maybe it is a new thing on the b+ cause this has only been out for a month or 2.

thanks for your message though i’ll get another one and try it again and look on the bright side there are worse things that you could have no warrenty for.

from jesse

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