OP failed to specify where this offer was made, between phone/chat support and in-person. If the device was reviewed in-store, there is a triage. If the device is completely dead, and won't enter DFU mode, then diagnostics can't be performed to isolate the issue further. There is a physical inspection, including the liquid contact indicator. Unfortunately, the LCIs are no longer externally visible for iPhone 14 and later in the US (
no sim tray). We don't know where OP is located, can only infer US based on one year limited warranty. I haven't serviced devices since this change, so I don't know if Apple skips to a whole unit replacement, instead of opening the device and checking LCIs first. In summation, it's not like Apple outright refused any sort of servicing without due diligence, because a repair is still a net profit they'd be silly to avoid.