Why my apple watch is not charging( recent change battery)?

Hi, I’ve just changed my apple watch series 1 battery and let it charge, the apple icon appears on the screen but disappears a few seconds after. Is it a problem with the charger or the watch? ( I recently bought an apple watch charger from amazon )

crwdns2893858:0crwdne2893858:0 crwdns2893862:0crwdne2893862:0


crwdns2889612:0crwdne2889612:0 0