iPhone went Black and steam on the camera

Good, I took my phone to Repairs and they are not giving me a full report of what happened to the phone, and that limits me to claim the phone under warranty and damage

this is what they said: "UNIT DOES NOT POWER ON BUT VIBRATES WHEN CONNECTED TO CHARGER. HDI ICC SHOWS THAT UNIT IS DRAWING LITTLE POWER. NO TRACES OF LIQUID DAMAGE. UNIT OUT OF WARRANTY QUOTE FOR WHOLE UNIT REPLACEMENT" " Kindly note that we, unfortunately, cannot specify what caused the fault as there is no evidence of lightning/ power surge, liquid or physical damage.

Therefore we have deemed it as a component failure as per the quotation and insurance letter provided."

Bu how can you (Deemed it as that) and dont have a full report? I know that the front camera was full of steam from the inside and started going blur and the screen turned black, If they do not give me a full report and the issue is there, I will have to take it even higher,

Who can I deal with from here? I need to get this issue sorted, cuz all I need is a full report of the issue of the phone.. phone cant just die and Apple says the don't know the issue or problem, its unprofessional.

All of this happened on the Apple (Core group)