Is it really liquid damage?

I booked in my laptop for repair on 09/04/2018 about my screen being very dim and not responding to brightness adjestments. The device was received by them on the 11/04/2018 and it was assessed for repairs then and then it took forever to get feedback each time i received feedback was that my laptop is being assesed and no outcome was given and on23/04/2018 it was said that my laptop has liquid damage and they don’t cover it. If it has liquid damage why did it take them that long to discover it and to make matters worse I only received their quotation on the 09/05/2018. My question still stands why did it take them so long to discover if it indeed has liquid damage, their service is off poor quality and I’m not satisfied.