As I mentioned in the comments, the flashlight test won't help you with your phone, as that only works with LCD based screens, not the OLED display yours uses.
Anyway, outside of possibly bent pins on the connector of the new screen, there wouldn't be anything you could do to fix it. The screen is pretty much an integrated assembly and either works or it doesn't, so at this point it seems pretty definite that you need a replacement.
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crwdns2944067:05crwdne2944067:0
Try shining a torch into the display. If the backlight isn't working, you should see something when the torch is shone on the display.
crwdns2934271:0crwdnd2934271:0 bananakat12345 crwdne2934271:0
@bananakat12345 Sorry, that advice won't help; the iPhone 13 Pro uses an OLED screen where the individual pixels generate their own light, so no backlight is needed on that display.
crwdns2934271:0crwdnd2934271:0 Jerry Wheeler crwdne2934271:0
Markus, have you tried the original display? If it still works the same as it did originally and the new screen doesn't, then it's most likely an issue with the replacement display. Let us know what happens with the old screen.
crwdns2934271:0crwdnd2934271:0 Jerry Wheeler crwdne2934271:0
Might pay to check the ambient light sensor is connected before going for a new display
crwdns2934271:0crwdnd2934271:0 Chris Stables crwdne2934271:0
just tryied with the lamp on the mobile. but the screen is pitch black. not a sign of something but the phone works with the old display that is cracked
crwdns2934271:0crwdnd2934271:0 markus hoffsten crwdne2934271:0