Brain Disfunction

Hi,
My friend of 16years old is in a condition of Brain Disfunction,he is breathing only with the help of ventilator.Doctors are not declaring as brain dead but they said there is 0.001% of possibility to recover him.But his parents dont want to take his ventilator out.He is in this condition for last 6 days.
Doctors saying some fluide in brain is not able to come out because of some block in the brain so pressure got created and stem got moved.

Plz suggest is there any possibility for him to recover,what we could do next and why he fall this serious condition in couple of days.He was normal active just two days before he said he is suffering from head ache every one thought its a normal head ache even he didnt felt unbearable pain.The day before last day he felt both head ache and vomitting we took him to hospital there doctor said it might be a virul fever and he gave some tablet the night he had the tablet and slept on next day morning we was not geeting up even after calls so his parents took him to hospital there also doctor kept him for trips(glucose) there is the final movement in his body we saw then we took him to the big hospital there they took ct scan and they said his body is not in the condition to take MRI Scan and above are the results(brain disfunction) they said.

How without major sympton he reached this serious condition.

Thanks,
Anand