Raspberry pi 3B+ noot booting with any sd, 3V3 pins not working

[Jordanaras]

I bought a raspberry pi 3B+ some months ago and it worked perfectly for some time. All of a sudden it didnt boot 4 days ago, so i burnt a new raspbian lite image in the sd and the problem persisted. I bought a new sd and again burnt the latest Raspbian Buster Lite and plugged in my pi with the official power supply. Still only the power light switched on, while act was mildly on and steady. I checked the 3V3 pins and they didnt output any voltage, while the 5V worked perfectly. I have read the sticky and it says that if the pisn arent working i cant do anything. Complete disappointment as it was my first pi and its not that easily available in my country. I also havent used the pins for anything that could cause damage other than a simple led.

[pcmanbob]

Hi.

As you have found the missing 3.3V on pin 1 of the gpio header means your pi is dead....

without knowing what you have connected to the gpio or how it was connected its impossible for anyone to say what you did wrong.

But even a simple LED can cause damage if you did not use a current limiting resistor in series with it.

some of the typical causes .

shorting 3.3V and 5V pins
shorting 3.3V pin to ground
connecting 5V to any GPIO pin
powering up the pi while is on a conductive surface