Sure, but the OP said they offered a repair. The question the OP wants answered relates to the CGA, and the answer is the retailer/supplier has, under the CGA, the right to repair a fault.
But the CGA says they can also choose to replace. If the board was 5-6 months old a repair would be reasonable but 1 week old brand new board? That's not reasonable.
where does it state that you have to agree its reasonable?
its a fairly minor fault in the scheme of things and certainly doesn't make the product unusable so a repair IMO is an acceptable solution.
better than them just saying no its your fault and leaving it there.