Mark Goodge writes:

What the law actually says is that:

goods which do not conform to the contract of sale at any time
within the period of six months starting with the date on which the
goods were delivered to the buyer must be taken not to have so
conformed at that date.

but with the supplier's get-out that the above does not apply if:

it is established that the goods did so conform at that date

But proof that a phone has suffered liquid damage (or evidence of damage
in any goods) does not prove that the goods 'did so conform at that
date'. All it proves is the state of the goods *now*, it gives no
evidence at all as the state of the goods at time of delivery to the
buyer.