When I'm using my RPi 3B powered by the micro-USB port (5V 2.4A) and I happen to use a USB extender for the power cable, the RPi 3 seems to boot up and work fine except for the fact that the red light simply goes out after successfully booting, with the green light still functioning properly. I can still use the console perfectly and do whatever I want like compiling with GCC and using peripherals.
When I don't use the USB extender cable, the RPi 3B's red light stays on forever while it functions, as expected? Note that the USB extender cable I am using simply lengthens the cable distance, it does not inject power and is USB 2.0. I think I may have ruined an RPi 3B by doing this, as a short while afterwards I had to buy a new one, as my old one refused to read the SD card and was stuck with a non-blinking red light. Typically a sign of death in my experience. I tried it on my new one once and it did the same thing, although it hasn't stopped working (yet?).
Can anyone explain this phenomenon? I've never heard of a Raspberry Pi 3 Model B still working and functioning seemingly perfectly without a red light. I feel like this is surely damaging the board? Whatever the answer may be, I'm staying away from the extension cable.