MANCHESTER – Erik ten Hag said he is no “Harry Potter” to magic up quick fixes for Manchester United after a demoralising 3-0 home defeat by Liverpool on Sunday.The Dutchman is already under pressure just three games into the new Premier League season after also losing 2-1 last weekend at Brighton.A shock FA Cup final win over Manchester City in May helped keep Ten Hag in his job despite finishing eighth last season — United’s lowest ever Premier League finish.The former Ajax boss was even handed a contract extension and backed with a £200 million ($262 million) spend on new players…