Samsung Stuck on Logo Screen - Android Q&A, Help & Troubleshooting

Hey everyone , I ran into some trouble with my device and I thought this is the only place I could find a solution,
I was trying to root my samsung tab a (2019) (SM-T515) , but something went wrong after flashing twrp ( specially made for tab a ) and ever since my phone is stuck on the main "Samsung galaxy tab A secured by knox" screen with a yellow triangle symbol below it , it isn't being detected by my PC anymore either. This is what I did in steps:
1)Unlock OEM
2)Go in download mode and flash twrp , it said "pass" and I had auto-reboot off , so I rebooted and got stuck here.
I have tried the power button , it doesn't do anything , also the volume up + power key (recovery mode) doesn't do anything either.
Also I tried the volume down + power button , it restarts the phone and puts it back to the same screen after this message ( see attached imgs ).
{
"lightbox_close": "Close",
"lightbox_next": "Next",
"lightbox_previous": "Previous",
"lightbox_error": "The requested content cannot be loaded. Please try again later.",
"lightbox_start_slideshow": "Start slideshow",
"lightbox_stop_slideshow": "Stop slideshow",
"lightbox_full_screen": "Full screen",
"lightbox_thumbnails": "Thumbnails",
"lightbox_download": "Download",
"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}
^ stuck on this

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Would a USB Jig work in this case?

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Hold Power + Vol Down for 7 seconds, then immediate switch to Power + Vol Up to enter TWRP. If that doesn't work, attached USB cable, hold Power + Vol Down for 7 seconds, then switch to Vol Up + Vol Down to enter Download Mode. From there you can flash a known-good OEM build with Odin.

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Magendanz said:
Hold Power + Vol Down for 7 seconds, then immediate switch to Power + Vol Up to enter TWRP. If that doesn't work, attached USB cable, hold Power + Vol Down for 7 seconds, then switch to Vol Up + Vol Down to enter Download Mode. From there you can flash a known-good OEM build with Odin.
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I tried but it isn't doing anything . I just can't seem to enter download mode whatsoever.

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bump , please help

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ItsHenry said:
I tried but it isn't doing anything . I just can't seem to enter download mode whatsoever.
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Click to collapse
It's possible. When I first started developing for this tablet, I gave up and was ready to let the damn battery drain to reset the device. After about a week, I tried again and finally got the timing right. You need to hold for just a little over 7 seconds, enough so that the reset begins and the screen goes blank. When that happens, immediately switch to the Vol Up & Vol Down combo. (Also, don't forget that you have to have the USB cable connected. It won't work without that.)

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Magendanz said:
It's possible. When I first started developing for this tablet, I gave up and was ready to let the damn battery drain to reset the device. After about a week, I tried again and finally got the timing right. You need to hold for just a little over 7 seconds, enough so that the reset begins and the screen goes blank. When that happens, immediately switch to the Vol Up & Vol Down combo. (Also, don't forget that you have to have the USB cable connected. It won't work without that.)
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Heres what I do ,
1. Attach USB
2.Reset it (vol. down + power)
3.This screen opens
4.I immediately hold Vol. Down + Vol. Up
5.After like 2 seconds, this screen shows up, demanding me to press the power button
6.I ignore it and keep holding vol. down + vol. up, after a while , it goes away automatically , and goes back to this screen
And stays there

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Ok , I do not know what I did , but somehow its in download mode now. well thanks for the help @Magendanz , what now , I flashed the original firmware , the tablet started, do I try to root it again?
Is your TWRP version ok for T515?
Also, I was asked to factory wipe the device cause the data was somehow corrupted , idk why was that cause , maybe the twrp version isn't stable? I don't know if I should try again or not.

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ItsHenry said:
Ok , I do not know what I did , but somehow its in download mode now. well thanks for the help @Magendanz , what now , I flashed the original firmware , the tablet started, do I try to root it again?
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I'd flash the OEM firmware, just to go back to a known-good state.
ItsHenry said:
Is your TWRP version ok for T515?
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Well, I don't have a T515, and so I really can't say for sure. I build the custom kernel from the latest SM-T515 kernel source and follow the same build process as I use for the T510, but I'm relying on others to test it. I can only say for sure that the SM-T510 builds work.
ItsHenry said:
Also, I was asked to factory wipe the device cause the data was somehow corrupted , idk why was that cause , maybe the twrp version isn't stable? I don't know if I should try again or not.
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Click to collapse
If you didn't install Multidisabler, then the fstab will require encryption. If you wiped it in TWRP, rebooting to system will insist the user partition be reformatted with encryption before it will proceed unless dm-verity is disabled.