Hi Alfie,
I hope the charge held through the night. 5 hours to charge is not too bad given they probably did not design the Zeo Bedside to fast charge the headband, and a slower charge rate should extend battery life. The fact that it did display the headband as charged is a good sign! From my experience Zeo put a lot of thought into the Bedside Unit design, so there may be life left in your unit.
We are all looking at the future of battery replacement (see post #101 this thread). Let us know how it works out, and if possible take pictures of the process and insides when it happens.
Thank you.