My money is on the charger base contacts. Any spilled coffee quickly finds it's way into them.
Try for a replacement from Ember.
Touch the top of each contact and push it down. It should move about a 1/8 of an inch. If you sense no movement then that is your problem. Pick at the stuck one with your fingernail to try and get it up.
I will replace the pair for $10 if you pay for shipping.