ASUS replacement laptops...no warranty?

[walpolepark]

My university son saved up and purchased a ASUS laptop for over £800. After a few months it started taking over 5 minutes to start up. With a month to go on the 12 month warranty he returned it for repairs to the supplier who sent it to the manufacturer. After a few weeks he was advised that a repair would take many weeks and he would be better off accepting a replacement (USED) laptop of the same specifications. Since he needed the laptop for university work he had little option but to take the replacement. The remainder of the existing warranty would be transferred to the replacement laptop, which he didn't realise at the time. The replacement laptop lasted less than a month and it stopped working. ASUS will not accept liability for repair. Surely a replacement laptop should come with some form of warranty since repaired laptops come with 3 months warranty. What stops manufactures giving customers replacement laptops that they know are faulty? Is the manufacturer infringing on any consumer rights by issuing customers with replacement laptops that do not have warranty and may stop working the very next day? What is my sons best course of action since he cannot afford the repair or a new laptop