Some have had success in cleaning corroded ecus with pcb cleaner and a soft toothbrush. I dont think they were as bad as your's though.
Hi Cosmic, i tried clean the PCB with acetone.. unfortunately few tracks and chip pins got already corroded due to water log. more over the the PCB is dual layer where layers connecting plated through-holes could have also corroded..
Between i got one new BCM from spares dealer for $150 BCM PQ-25 6RU937086H( upgraded one compare to my factory fitted 6RU937084A).
Hope i need to un-check Airbag and ABS under CAN gateway installation list. air-bag and ABS warning on instrument cluster(my Fabia doesn't have ABS and air-bag fitted).
will update you once figure the options.