Fitbit Product Experts Alumni are retired members of the Fitbit Product Expert Program. Learn more
Hi @Lofty - proceed with caution in case it got water in it but it may also just have a flat battery.
Dry it and start a charge session, check if its getting hot because of internal shorting, if so stop immediately.
If the watch displays charging state and even starts normally, then it was a flat battery. Tap it a few times after some minutes to see if there is a battery level shown.
If it remains dead take it to where you bought it for a refund or replacement with a new one over the counter.
Author | ch, passion for improvement.