display faulty after installing new one

Hello together,

my first time here - if I´m wrong in this section please tell me.

I changed my cracked display, no problem with the instructions from here, till I glued the new one in. The display was fine, but very unresponsible or opened apps by itself. So I took it out again, to see if I made a mistake somewhere. Checked the cables, but found nothing.

Put it together again, and now there are only stripes on the display.

Has anybody a clou what could have happend?

Broken cable or killed the new display?

Thanks in advance.

Rainer