Charge 5 battery issues

[Hellam]

After only 5 months of use - started having issue with battery, either not charging after putting it in charge overnight or fully charged 100% but then draining completely after 1-2 hours!!  I will never buy a fitbit again!!  Not cheap either - cost me over £100

Moderator Edit: Clarified subject

[Talahthas]

Welcome to the Fitbit community, @Hellam!

Sad to hear that your Charge 5 currently isn't working as expected. To hopefully get things fixed, please have a closer look here as a first approach:

Why isn't my Fitbit device's battery charging? 

You also might want to to try restarting your device to get it back to working order. Before doing so you should make sure you've synced your device to not lose any data tracked so far. Also you should verify that the charging contacts on your device are clean and the charging pins on it's charging adapter are clean as well and can move flawlessly. In doubt, please have a look here:

How do I clean my Fitbit device?

Next please closely follow these instructions as timing is crucial for this procedure:

1.) Connect your Charge 5 to the charging cable which has to be connected to a reliable power source.
2.) Press the button located on the flat end of the charging cable 3 times within 8 seconds(!), holding each press for about 1 second(!).
3.) Wait around 10 seconds until the Fitbit logo appears on your device's display.

I'd like to point out that it sometimes requires more than one attempt to restart Charge 5. So, before throwing the towel, please give it another try.

If that really won't work for you, please try if changing your device's clock face will get it back to working order. Here's how to do that:

How do I change the clock face on my Fitbit device?

Finally I'd suggest checking what might be draining the battery of your Charge 5 by having a look here:

Can I extend my Fitbit device's battery life? 

I'll keep my fingers crossed.