I picked this up from this thread. I believe this can be used as a test to see if it is the Audio Chip IC that is the problem, Turn your phone off. Then turn it on again, put pressure on the screen as shown in the image as the phone starts to boot. This will press the audio chip on to the circuit board. If the phone boots normally, it is the the Audio Chip IC. Here is the link to the article as posted earlier. http://www.fixstop.com/blog/iphone-7-stuck-at-apple-logo-reasons-and-how-to-fix/ More Tests : (1) Open FaceTime (2) Start dialling someone. When the phone starts to dial, press in the same place. If FaceTime works, then once again, it is the Audio Chip IC. (3) Try a normal phone call, as soon as the phone starts to dial, press in the same place and see if it works, if it does, it is the Audio Chip IC (4) Other tests you can perform, Record a video front & back & press the screen, Record a Voice Memo & press the screen Hope this helps.
I had the similar issue with GPS not being accurate on an iPhone 6. Replaced wifi antenna and hey presto fixed. This is cheap enough option to try. On a side note, there are some techs on here that are just down right rude. Get a grip please, not everyone is a pcb genius like you.
Yes, seems you have water that has got into the screen and maybe into the device. You need to switch the iPhone off now and have it checked out. If it is just the screen, that can be replaced, but if water has got into the phone, the phone will need to be dismantled and the circuit board cleaned to remove corrosion and residue. This is usually done by putting the main circuit board through an ultrasonic cleaner. Be aware there may be components on the main circuit board which have been shorted out, so this may or may not cost you more than the device is worth. Certainly worth trying a new screen first though. Here is the iFixit screen replacement guide… iPhone SE Screen Replacement
Probably a swollen battery is pushing the screen away from the casing. Usually happens when a mobile is left plugged in for long periods of time. You may or may not need a new screen, but you certainly need a new battery. Here is a guide on how to change the battery. Google Pixel XL Battery Replacement
Phone may not boot and the screen may not even work without the home button connected. Are you 100% clear that it is the light sensor not working or the proximity sensor? I have never seen that white film on any of the screens I have replaced. Try this app to test which sensors are working. I am not sure, but the camera may be the one that is used for the light sensor. The app is free and brilliant. https://itunes.apple.com/gb/app/testm-check-phone-report/id1242371446?mt=8
You may have main speaker failure. Please give more info, like what have you tried, what conditions is the iPad in on a regular basis, has the devoice been dropped of had any water damage or been opened?