Ligthening Symbol on Power On.
I have been using a number of my Raspberry Pis recently to connect to devices such as ESP32 S.o.C. and HX711 strain gauge. This has meant swaping around Pi devices, power points etc. With all this going on I decided to try connecting a PIR to my Pi3 with the camera, to make a simple motion detector. So powered-up the Pi3 and…..nothing, or almost nothing. It started the boot sequence, screen lit up, with a strange yellow ligthening symbol top right then blank again, only for the sequence to repeat.
Quick search, and bingo – the sysmbol means the Pi is not getting enough power. In my search for power supplies with the mirco USB connector, I had picked up one for an old Samsung phone…. delivering 400mA and 4.2V. Not surprisingly, the Pi didnt like it very much.
The good news though. Replaced power supply with correct unit and all was well. So no harm done.