I had the same issue. All I did was pull out the trap at the bottom front and clean it out. It was full of screws, tie wraps, and other small crap. Caused it to throw codes and not drain. hope this helps https://www.youtube.com/watch?v=mwDKISK6...

Hey there! I just replaced a Galaxy S7 rear camera lens for a customer. I didn't have to remove the whole back glass. I just used my heat gun to heat up the camera lense, took a sharp plastic pry tool and gently poked through the middle of the lense without touching the actual camera. I worked the lense up all the way around until it came off as a whole. Cleaned the remaining adhesive off with some alcohol and pry tool. If you're wanting to open the whole back glass of the S7, a heat gun(good hair dryer), some decent plastic pry tools, and some playing cards help. Don't cook it but get it hot to the touch. Gently pry around the edges of the back glass all the way around the phone. Use a playing card to break the adhesive bond but sticking it between the glass and mid frame and sliding it along. Hope this helps!!

Most likely display touch might not work again until the phone main board is ultrasonic cleaned, connectors cleaned and checked out by a mobile technician. Likely needs a new display installed..hopefully that is the only issue after a good cleaning. I mainly do screen replacements so maybe someone else has some good info.