[Galaxy S 4 Q&A, Help & Troubleshooting] CharlJ_SA:
I am having a very frustrating intermittent blank screen problem with my Galaxy S4 (GT-i9505). In its current state it has stock lollipop from Sammobile (I9505XXUHOB7_I9505BTUHOB4_I9505XXUHOB7_HOME.tar) flashed onto it. No root.

Randomly after locking my screen, or after a screen timeout, the screen won't turn back when trying to unlock it with the side or home button. The phone and capacitive touch still works completely in the background and I can answer calls and hear notifications coming through, but no display. The display turns back on after a while, but troubleshooting has become difficult as this problem is extremely irregular.

It started when I had stock Kitkat installed from Sammobile. I have rooted my phone previously but the Rom upgrade to latest KitKat took it back to stock. The screen would go blank and after a couple minutes it would turn on when I unlocked it and it would be ok for a couple days. But then the blank screen problem would come back, and its length has seemed to get longer aswell. This includes no display when the phone boots up.

Things I have done so far to try fix it (during the periods when the phone display magically resumes):

- wipe cache and factory reset (no luck)

- reflash stock kitkat Rom, wipe cache and system data (Phone was fine for about a week but intermittent blank screen problem came back)

- Take battery out and drain residual capacitance by pressing buttons while battery out (sometimes worked but extremely irregularly and eventually stopped fixing the problem)

- Put phone on charge and try unlock or turn phone on (sometimes worked in the beginning if I left phone on charge for a while but this method doesn't work anymore)

- Flash lollipop Rom (I9505XXUHOB7_I9505BTUHOB4_I9505XXUHOB7_HOME.tar) via odin, wipe cache and data before and after flashing (phone worked for about a week but intermittent problem eventually came back)

- Reflash same Rom as above AND .pit file (CSB_signed_Fusion3_EUR_0325_V2.pit) via Odin to re-partition tables in case of corrupt partition (Phone was fine for a day but when I woke up in the morning the phone screen wouldn't turn on so this didn't seem to solve the problem)

As it stands, my phone's display pretty much stays on for a day with perfect function, and then randomly the display won't resume after locking it, and stays this way for about another day.

What I would like to know is if I am COMPLETELY starting fresh when I flash with odin, re-partition with a .pit file, and wipe the cache and system data in stock recovery after the odin re-flash. Or is it possible that in an unrooted phone with stock recovery, I am missing something that might remain corrupt and is causing this intermittent problem. Maybe dalvik cache? Or does this get wiped with the odin reflash?

To me it seems like some low level system file is building up and eventually getting corrupt. I am not 100% sure but I doubt it is a screen hardware problem since the display problem only happens when turn the display off and on with the side lock button (it never turns off unless I tell it to turn off or after a screen timeout and it never turns off if I knock it or bump it)

I would really appreciate your help. There is a lot to read here but I wanted to thoroughly explain my situation. Taking it in for repairs is my absolute last resort.

Thanks!