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I have 2 identical 4Bs: the one older one that used to work and the new one I ordered yesterday.

With all the same cables and SD card, the new one works fine, the other one is giving me the rainbow screen.
Does this mean the other one is irreparably broken? I ask because it seams really weird for a computer to be perfectly able to produce a rainbow pattern but then not being able to boot any further than that. Hardware failure usually results in total failure.

So is there a way to revive the old Pi? I tried both NOOBS and Buster but both only work on the new one. I also used a 3Amp USB C supply and didn't get any lighting bolts on the new one.

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9
  • Ah, let me see. Once upon a time I earned my living doing quality control of semiconductor devices testing. We accept or reject millions of ICs each day. We sample test (up to 100% on all tests, or only 20% of some tests) and.classify good guys into grades of consumer, medical, military, space applications. Each grade has a spec with TOLERANCE (sort of max, min, avg etc). What I am trying to say is that NO device,.even of the same grade (same lot, same wafer/chip), are IDENTICAL! :) PS - my IQ is 97, but my twin brother 98!
    – tlfong01
    Dec 18, 2019 at 12:32
  • Have a look at this: lifehacker.com/… Since the card is working on the other raspberry then it's not the card, but it could be the socket on the old raspberry or what ever is supposed to read from that sd card. According to them, "The rainbow screen appears on every boot as a test of the GPU" and before it loads the kernel.img
    – papatrexas
    Dec 18, 2019 at 13:24
  • I dont think thats helpful since i can rule out external factors like the card and the psu
    – user2741831
    Dec 18, 2019 at 13:36
  • @user2741831 Did you see where papatrexas said "socket?" Your broken Pi seems to be behaving as though it can't read the boot files. If you really have a 3 V power supply, dump it. If it's a typo in the question, please fix it. For the Pi 4, and at the moment, I suggest that the official power supply is the only safe option. That will change as other options become available, but chargers with e-marker cables simply won't work.
    – Bob Brown
    Dec 18, 2019 at 17:14
  • Perhaps it'd be possible to debug the Pi with the UART: raspberrypi.org/documentation/configuration/uart.md
    – user96931
    Dec 18, 2019 at 17:27

1 Answer 1

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With exactly the same external hardware and SD card content, the only difference between two devices is the bootloader. I would try to use the bootloader recovery image on the defective Pi before discarding it.

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  • I did. It did nothing
    – user2741831
    Jan 2, 2020 at 18:20
  • @user2741831 Then it should really be the hardware.
    – Dmitry Grigoryev
    Jan 4, 2020 at 13:44

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