When the green LED of your Raspberry PI does not flash, the system can’t successfully access the microSD card. So you are probably in one of the following situations:
- You did not insert a preformatted and flashed microSD card
- Your microSD card is corrupted, and does not work anymore
Solution:
You should always keep a copy of the ISO image of your operating system. If you don’t, please download one at http://downloads.raspberrypi.org/raspbian_latest
Flash a new microSD card with the OS (if the old one is corrupted, you should avoid using it again). You can use balenaEtcher: it’s free and has the same GUI for Linux, WIndows and MAC.
The microSD has three primary parameters:
- Memory capacity
-
- MicroSD = up to 2 GB
- MicroSDHC (High Capacity) = from 4 GB to 32 GB
- MicroSDXC (eXtended Capacity) = from 64 GB to 2 TB
- UHS Speed class
-
- MicroSD Class 2 = 2MB/s
- MicroSD Class 4 = 4MB/s
- MicroSD Class 6 = 6MB/s
- MicroSD Class 10 = 10MB/s
- MicroSD UHS-I 1 = 10 MB/s – Bus Speed 50-104 MB/s
- MicroSD UHS-I 3 = 30 MB/s – Bus Speed 50-104 MB/s
- MicroSD UHS-II 1 = 10 MB/s – Bus Speed 156-312MB/s
- MicroSD UHS-II 3 = 30 MB/s – Bus Speed 156-312MB/s
- Video Speed Class – V6, V10, V30, V60, V90 again it’s the sequential write speed
So, the next time your system refuses to boot, check the green LED on your Raspberry PI and eventually flash a new ISO image. That’s all!