Iphone 11 Pro Blackout (Main logic board problem)

Hello There. Pardon for my bad english grammar. I just want to ask. My girlfriend has her iPhone 11 Pro 256gb brought here on PH last 2019. and suddenly last month, june 2021. Her iphone were unable to power on nor charge it. it has no display (completely blackout). And we went to one of the Apple authorized service center for repair. and it finds out that unit has Main logic board problem and it passed on Physical and Water damage exam test (For verifying that unit has no user's negligence). And we contacted Apple SG for consideration request that iPhone must be repair for free of charge even if its out of warranty. And Considering the unit itself is on its excellent condition before the incident happens. and unfortunately, Apple SG said the unit has declined for repair due to out of warranty coverage. Please help us. Unit itself is not yet fully paid on installment basis yet we are paying and the phone is already broken in less than 2years upon buying. Thank you so much. God bless you