I am new in this world of Raspbian. I just bought a Raspberry Pi 3 model B with a power source with an output of 5 V 2500 mA. So I get one of my SD cards of 16 GB, I have download the .iso image of the Raspbian system from here and finally a software called Etcher that turned very easy to put the image in the SD. So I flashed the SD card, put it into the Raspberry, but when I connect to power supply, nothing appears in the monitor (HDMI connected previously), not even the so called Rainbow screen. Am I missing something?? This is getting so frustrating.

PD. I forgot to add, a red light is visible inside the case when the power supply is connected, so electricity is flowing apparently.

  • What TV/Monitor are you connected to ? What resolution is it ?
    – CoderMike
    Nov 11, 2017 at 23:33
  • Have a look at this excellent troubleshooting guide: elinux.org/…
    – MatsK
    Nov 12, 2019 at 19:22

2 Answers 2


I once flashed an SD card improperly (that sounds so wrong.) Anyway, I was trying to cross-compile a kernel for the Pi and I buggered it up, so the SD card would not boot. BUT, I did see the Rainbow screen of colours. And that's all I saw as it did not progress. So if the card is bootable, you should always see the Rainbow screen, which usually flashes up for a brief second at the start of boot up, but if the card won't boot, the Rainbow remains on the screen till you turn the RPi off.

Now I just did a quick couple of experiments:

Experiment #1: I booted up my RPi3 with no SD card in it. I got a black screen and nothing more.

Experiment #2: I booted up my RPi3 with an SD card that had a RPi1 kernel on it. That displayed the Rainbow screen and was stuck on the Rainbow screen.

The red LED comes on in both cases. I think I saw the green LED flicker for experiment #2.

So double-check that your SD card is inserted correctly (e.g. the correct way up.) Insert your SD card into your PC and confirm it looks ok in a file manager. Try another SD card, preferably one that you know boots on a RPi 3 (e.g. one from a mate?)

  • If there is no card or a card that is unreadable, on most models the green ACT will never light. The exception is the Pi 2, on which the ACT light will come on and stay on (as opposed to flickering for normal operation, or blinking to indicate an error booting).
    – goldilocks
    Nov 12, 2017 at 18:45

Normal behaviour for a RPi3 during boot is to have a red LED on to indicate it has electrical power and tyo have a green LED on (right next tot he red LED) to indicate SD card activity. I suspect your SD card was not flashed properly. Follow the instructions here.

  • This is basically a comment and/or a link-only answer right now.
    – Brick
    Nov 12, 2017 at 13:36
  • @Brick It may be a bit short, but it's definitely not a link only answer. I made it a bit more verbose for you.
    – tlhIngan
    Nov 12, 2017 at 18:03

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