Hello Everyone,
I was also having the same issue since, I have replaced my broken screen 2 times.
Problem
Screen goes blank when call in progress (As soon as you click on call someone). Power button and volume button doesn't work.
I was searching for the solution online and came across this thread. But, unfortunately, couldn't find the solution.
So I went ahead and doing some trials and luckily found a way to get through when this problem occurs.
Solution
Step 1 Open your "Menu"
Step 2 Click on " Settings "
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Step 3 Scroll down to " System " settings and click on " Accessibilty "
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Step 4 The following screen will appear
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Step 5 Scroll down to to see an option called "Power button ends call" , Turn this function "On"
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Step 6 Now, save your "settings" and come to your "Home Screen"
Now, you can end your calls just with "Power button". When your screen goes blank and nothing works (Check dialing your customer care).
P.S : To use "in call functions, you need to plugin your headphones and the screen will appear normally. (If you anyone knows how to solve this without plugging headphones, Please do reply me with the solution.)
Hope it will be helpful to someone.
Thank you.