Pi4 No Longer Boots

[BluesKamikame]

My brother gave me an RPi4 (4GB) with the official power supply recently as a gift, and it died after a few weeks of use. I'm hoping I might be able to resurrect it, or at least learn something trying.

Pre-death, the pi would occasionally hang (pressing num lock wouldn't toggle num lock light, Pi inaccessible via ethernet, etc). Rebooting would fix the issue, but freeze would happen once every 1-3 days.

I had the Pi running one day, and plugged in my laptop cable into the same power strip. As I pressed the plug into the socket, I heard an arc from the socket and the Pi immediately died (no video output, red power light blinking). It now only blinks the red light, doesn't boot. I tried another power supply, and still only a blinking red light. I tried my SD card in a friend's Pi4, and that successfully booted.

Any ideas on how to diagnose it? I see there are test points on the bottom of the board, and I have read the power light might blink when what should be 5V falls less than 4.6V, so that might be the first check I should make. I'm having trouble finding a map of the test points, though.

Thanks in advance for any ideas.

[davidcoton]

Test the 5V and the 3V3 supplies at the GPIO header. Use DuPont (jumper) wires to make sure you don't short anything, if you do short it then you will kill your Pi (probably).

Does anything on the Pi get very hot?

It does sound like a dead Pi, but we will probably never know exactly what went wrong. Plugging things in and out on the mains side should be safe, unless you had a static electrical charge on the laptop, or there is some wire connection between Pi and laptop.

[BluesKamikame]

No perceptible heat at all, as far as I can tell. I'll borrow my friend's multimeter on Monday or Tuesday and report back on the voltages.

Btw, the laptop was off at the time and has no battery (removed because it's old and just a dead weight).

[BluesKamikame]

Finally was able to test with a multimeter, and here are the results. Pandemic made it difficult to find a new apartment, let alone get my hands on a multimeter.

Voltage measured between TP1 and TP2 was 0V, whereas I understand it should be between 4.75V and 5.25V.
Voltage measured between pin 9 (ground) and pin 1 (3.3V out) was 0V.
Voltage measured between pin 9 (ground) and pin 2 (5V out) was moving between 0.1V and 0.7V.

[davidcoton]

Something is definitely not well, even if not quite dead.

I can think of three possibilities:

1. The power strip (or one outlet on it)
2. The power supply (or the connected cable)
3. The Pi

OR, if you are really unlucky, some combination of the above (which gives another four possibilities, plus the variants )

I would test each by substitution, which is easy if you have spares but tricky if you are locked down with only the one Pi.

We always need more Pi!

[bensimmo]

I'd be looking at a dead PSU, so I would try another. What are you using as the powersupply.
all the problems before may be accounted for by faulty power and slight change from the arc just took it (PSU) over the edge to protect itself/destroy itself.

I could be wrong of course, it may have also taken out the Pi. but given there is no usable voltage coming out of the PSU...

though....
TP1,2,3 are all +VCC directly in front the usb-C connector.
you need to compare them to ground e.g. TP7,8,9,12

so TP1 to TP2 should have been 0V

[BluesKamikame]

I'd be looking at a dead PSU, so I would try another. What are you using as the powersupply.
all the problems before may be accounted for by faulty power and slight change from the arc just took it (PSU) over the edge to protect itself/destroy itself.

I have been using the official PSU (KSA-15E-051300HU), although I tried my cellphone charger which can also output 3A with no luck. Multimeter measurements were basically the same between both PSU's.

[kingfish]

I also have a nice red blinking PI 4. After it did not work with the original power supply. I tried with a more powerful power supply and there I could see that the PI was consuming 5 Amps (maximum of the PSU). I did not investigate further because I unplugged it very quick.
My assumption is that the original PSU ist just not able to keep the voltage up when such an amount of current is pulled. But still I have no idea what is broken in the PI.

[cleverca22]

I also have a nice red blinking PI 4. After it did not work with the original power supply. I tried with a more powerful power supply and there I could see that the PI was consuming 5 Amps (maximum of the PSU). I did not investigate further because I unplugged it very quick.
My assumption is that the original PSU ist just not able to keep the voltage up when such an amount of current is pulled. But still I have no idea what is broken in the PI.

if its pulling 5 amps when you turn it on, it feels like something is shorting hard, and the power supply is shutting off to save itself (causing the red led to go out)
then it turns on again, thinking the fault has cleared, but it hasnt, so it keeps turning on&off