Apple Watch series 5 unresponsive

Hello

I have an Apple Watch series 5 that won’t seem to turn on? I noticed it last night and thought it might have just been dead flat so I left it on charge for about 8 hours while I was at work so I know it is charged. When it is on charge the Apple logo appears but doesn’t go away only gets brighter then fainter repeatedly. When I take it off charge the screen just goes black and is completely unresponsive.

I have tried the hard reset of holding down the power button and crown multiple times whilst it is on charge with no success. The Apple logo goes away then once it reboots it stays on the screen and nothing changes. I have unpaired my watch (and now can’t pair it as I can’t get past the Apple logo when it’s on charge) and have tried to reset hole on the side but nothing seems to be working

It was a Christmas hand-me-down present from my parents and I can’t afford a new one so I’m really hoping it’s something simple to fix