Charging while on Power Saving mode

I have just remembered something, when my micro-usb plug got burned while charging, my M8 was in the Dot View cover (in which it contains a magnet) so could that be a reason for what happened?!

Sent from my HTC One M8
 
That I don't know. I haven't had any experience with that case, but I'm pretty sure HTC would have made sure it wouldn't be an issue before releasing the case.
 
Either way, after that incident I started charging my M8 without any cover/case, so that if it got heated-up the heat will not be held/trapped by it.

Sent from my HTC One M8
 
Just felt my galaxy s5 charger getting really hot. Had that burnt smell too. I switched over to another samsung charger and had the same problem. This is a new issue so I decided to check what I had done differently today. Only thing different that I have noticed so far was that power saving mode was on, so I decided to check this issue online and ended up in this forum. Charger still works. Will try again later and see if it resolves after turning off power saving.