It sounds like the display or display connector might have been damaged due to the overheating issue. Here’s what you can try to fix the Nokia Lumia 1320 blank screen problem:
=== ***Step 1: Soft Reset*** ===
Try forcing a restart by pressing and holding the ***Power + Volume Down*** buttons for about ***10-15 seconds***. If the phone vibrates, wait a few seconds to see if the screen turns on.
=== ***Step 2: Check for Screen Response*** ===
Shine a flashlight on the screen at an angle. If you see faint images, the ***backlight might be dead***, which would mean a screen replacement is needed.
=== ***Step 3: Connect to a Computer*** ===
Plug the phone into a PC and check if it's recognized by Windows. If the PC detects it, but the screen stays black, it’s likely a ***display issue*** rather than the motherboard.
=== ***Step 4: Hard Reset (if necessary)*** ===
If there's no response, try a ***hard reset***:
# ***Turn off*** the phone (or hold Power + Volume Down until it vibrates).
# ***Press and hold*** the ***Volume Down*** button.
# While holding Volume Down, press the ***Power*** button briefly until you see a "!" symbol.
# Press the following buttons in order:
** ***Volume Up*** → ***Volume Down*** → ***Power*** → ***Volume Down***
# The phone should reset, but ***you will lose all data***.
=== ***Step 5: Open the Phone & Check the Display Connector*** ===
If the phone still doesn't turn on:
* Open the phone (you’ll need a ***T4/T5 screwdriver***).
* Check the ***display connector*** (near the motherboard) and reseat it.
* If the connector looks fine, the ***display itself may be damaged***, requiring a replacement.
=== ***Step 6: Replace the Screen*** ===
If reseating doesn’t work, you’ll need a ***new LCD screen*** for the Lumia 1320. You can find them on eBay or repair sites. Replacing it requires ***careful disassembly*** but isn’t too difficult if you follow a YouTube guide.