Why does my screen stay black but touchscreen works? (Pro 6)

Hello,

1) I have an issue with my Surface 6 Pro, which I bought used with a broken display. I replaced the screen. When I turn it on, the backlight makes the screen bright for a few seconds, then it stays dark. When I connect the device to an external monitor, everything is shown there. I can even use the touchscreen of the device. Nevertheless, there is displayed nothing on itself. Which is weird, because the screen turns bright short, so there is a working connection somehow (I even tested 2 flex cables).

2) The weird thing is, I tested the same thing with the same screen on a Surface Pro 5 LTE Advanced. Same thing there, except, one time, the Surface Logo was shown. Otherwise, same problem. In addition to that, I replaced the battery on the second device. A small LED right above the battery turns on when I connect the charger. The device boots like the Pro 6 (nothing on screen except the short brightness after pressing the power button). But it also turns off immediatly when i remove the charger. When I first inserted the new battery, the LED also turned on just from the contact between mainboard and battery. This is not the case anymore and I dont know why.

Under windows, the battery charges regulary. Charger removed - device dead instantly. Cant turn on without battery.

Added: With the Pro 5, the LED also lights up when I completely remove the battery and connect the device to the charger.

crwdns2893858:0crwdne2893858:0 crwdns2893862:0crwdne2893862:0

crwdns2894050:0crwdne2894050:0

crwdns2889612:0crwdne2889612:0 0

crwdns2893872:0crwdne2893872:0:

@jules132 just to clarify your Pro 5 and your Pro 6 (are a 1796 and 1807/1809 respectively? The errors your describe are usually related to a compatibility issue with the LCD.

crwdns2893770:0crwdnd2893770:0crwdne2893770:0

Yes, the Pro 5 is a 1807 and the Pro 6 is a 1796. This is the display I use: https://de.aliexpress.com/item/400036931.... Thx for ur help.

crwdns2893770:0crwdnd2893770:0crwdne2893770:0

And, for further clarification, I have the flex cables from the Pro 5 and also these which I had to order since the ones from the Pro 6's screen were broken. https://www.chipspain.com/en/spare-parts...

They are the same as the ones for the Pro 6 as far as I know.

crwdns2893770:0crwdnd2893770:0crwdne2893770:0

Same thing with the original, broken screen of the Pro 6. Either its both cables or both devices with the same issue. Would be weird if its both LCDs. Its incredible, I wanted to safe money and now it seems like I wasted a lot.

crwdns2893770:0crwdnd2893770:0crwdne2893770:0

crwdns2892346:0crwdne2892346:0