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I have a problem with my Raspberry Pi. When I plug in the power, the device fails to power on. The POWER LED turns on, but nothing else happens. My display still says No signal, the OK LED does not turn on or blink and network LEDs stay unlit even though the cable is inserted.

Basically, the symptoms are the same as if I tried to turn the Raspberry Pi on without an SD card inserted. I last used a Raspberry Pi a week or so ago and it worked fine. I've checked if the SD card has maybe died and it is working fine on my computer. I've tried reflashing it with a fresh Arch image but still nothing.

The power supply and the USB cable are almost certainly adequate (5.0V with my multimeter between TP1 and TP2 and I've never had any problems even when running intensive computation and having external USB devices attached)

The funny thing is... if I hold the PCB and the SD card together with two fingers, the Raspberry Pi DOES turn on, but the boot process freezes (no kernel panic or anything, just hang) when I release it.

What could be the cause of this problem? Is it more likely that the SD card is indeed faulty or is there a problem in the Raspberry Pi itself?

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Have you checked the physical connection between the card reader and board and between the card reader and the card itself. It sounds like you have a bad connection or card and can't reliably read the card. I would also try another card. –  Steve Robillard Jul 1 '12 at 12:57
    
It seems fine. What is even more bizarre is that once the system boots, SD card works even if I release it. –  Tibor Jul 1 '12 at 13:00
    
In that case I would definitely try a new card because once booted it doesn't need the boot partition. –  Steve Robillard Jul 1 '12 at 13:01
    
I had similar symptoms but it was not fixed by holding the PCB and SD card, I had to reflash the SD card and then it was fine but I observed the same symptom where only the power LED was on and nothing else so your issue sounds strange.... –  EdChum Jul 1 '12 at 14:53
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Check out this Wiki for almost all answers to problems related to booting the RPi: elinux.org/R-Pi_Troubleshooting#Power_.2F_Start-up –  Sjaak Trekhaak Jul 2 '12 at 8:38

3 Answers 3

up vote 6 down vote accepted

It sounds like it could potentially be one of two things:

  • A problem in the SD card meaning that when booting, it struggles to access the boot partition correctly (which would explain why when you boot and let go, it freezes again)

  • A problem with the physical SD card slot in the Pi - one of the contacts could be broken or faulty meaning that when you squeeze it it makes the contact again and works ok.

The easiest thing to do would be to try another SD card, and then perhaps potentially another Pi if you can get your hands on one. Until that, it's quite difficult to say which one of those issues it likely is.

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if I hold the PCB and the SD card together with two fingers, the Raspberry Pi DOES turn on, but the boot process freezes (no kernel panic or anything, just hang) when I release it.

There's a problem with the card connection.

It seems fine. What is even more bizarre is that once the system boots, SD card works even if I release it.

If the system is running idle, it wont be interacting with the SD card. In fact, some of the boot process should be occurring in RAM. I would expect it to only halt when reading the image, starting daemons or mounting filesystems.

Try creating or copying files, or unmounting filesystems when the system is 'running' after you help it boot. You should find that this is when it fails.

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But I can cat files normally, it is not that SD card would be idle. –  Tibor Jul 2 '12 at 7:07
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@Tibor cat is hardly a demanding operation. Try copying files. Writing could be the problem. –  Jivings Jul 2 '12 at 7:29

Are you using a MicroSD Card adapter? Don't do that. Use a SD Card.

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The use of a microSD card adapter is not discouraged and many of them actually work with the RPi. –  Morgan Courbet Jan 3 '13 at 9:37

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