My apple series 4 watch has a red snake or a green snake not even reaponding to force restart

Hi my battery on apple watch is switching between green n red snake its on charging for almost 2.5 hrs power reserve mode i cant change till it gets swtched on .. tried force restart apple logo isnt appearing .. can u sugeest an alternative tried the steps already you have mentioned

Its not turning on its kept on charging at times show green snake at times red snake