On Wed, 31 Jan 2018 22:56:11 +0100, Thomas Prufer
wrote:

Possibly the charger output was shorted?

.... and the photo shows a NTC. Those are sometimes used as an inrush current
limiter. Switching the charger on and off frequently in a short time can defeat
the NTC, causing the fuse to blow.

Replace the fuse, and see!


Thomas Prufer