My RPi B+ stopped booting suddenly after 1month working. I try 4 different usd cards and for all of them act (green) led flashes 4 time and no video and no power on usb ports and ethernet. I know it means start.elf not launched, but new NOOBS seems not having start.elf. I try formatted usd and act led is on permanently. Even I deleted bootcode.bin and act led is on permanently. So RPi seems have access to usd card and I don't know what the problem is. When usd is inserted clock pin of usd has no voltage (dc or ac). Can someone help me?

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    I assume you have checked something like elinux.org/R-Pi_Troubleshooting#Power_.2F_Start-up At a guess I would look at power supply, what is voltage? And don't go deleting stuff - this isn't going to help. – Milliways Oct 19 '14 at 23:15
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    I think first step would be to check voltage, I bet there is a problem. – 10robinho Oct 20 '14 at 10:50
  • I check all test pads of supply voltages and they all are ok! – AmirAhmad ZiaeePour Oct 21 '14 at 9:40
  • I would check the PSU as the other people have suggested. Second, which SD card are you using? Some SD cards simply refuse to work with the Pi? – RPiAwesomeness Jun 2 '15 at 0:43
  1. Try checking if the voltage is 5v,if it is higher or lower than 5v it will not work.

  2. Check SD card storage space,sometimes even if it is 4gb,which is the minimum storage space required for rpi it will not work,so try 8 or 16gb.

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  • I can confirm Pi's work fine with 4GB cards. Standard rasbian wheezy even without deleting any packages. Agreed, there's not that much space left, but it works. – EDP Aug 1 '15 at 10:19

http://elinux.org/R-Pi_Troubleshooting#Green_LED_blinks_in_a_specific_pattern This link states:

4 flashes: start.elf not launched

It probably means your NOOBS got a bad case of corruption. If you used the same file stored on your computer each time, download it from the RasPi website again.

Question: did you see the happy-rainbow-GPU screen?

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First, I do not see any mention of the red light.

Second, no mention of voltage readings at the 5V and 3.3V pins.

At the very least we would need that much information in order to know whether the internal voltage regulator itself burned out.

4 flashes of green probably means the circuitry is actually working but that it cannot read the SD card. This can be due to too many insertions/removals.

Or, as mentioned in another answer the software on the card may be bad, or the card itself may have gone bad.

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