Screen needs several attempts to turn on (A311D)

Bringing this up again after some while: After a period of flawless operation, my Reform started this strange behavior again. Sometimes the screen just won’t turn on at startup. Meanwhile I developed some paranoid/esoteric/desperate measures: Like thinking if I move the screen a view degrees than it will more likely turn on or putting in or pulling out the power supply will help to start it up.
I managed to compare the outputs with my UART Adpater. The difference I can make out is as follows:

Output with Screen turning on:

Starting kernel ...

[    3.273530] DEBUG ti_sn65dsi86: burst mode enabled
[    3.312944] DEBUG: dw-mipi-dsi VID_MODE_TYPE_BURST
[    3.373183] DEBUG: dw-mipi-dsi VID_MODE_TYPE_BURST

Debian GNU/Linux 13 tontonkatze ttyAML0

Output with Screen NOT working:

Starting kernel ...

[    2.985108] DEBUG ti_sn65dsi86: burst mode enabled

Debian GNU/Linux 13 tontonkatze ttyAML0

Has somebody an idea how I could proceed? Could it be a mechanical problem with the screen-connection to the graphics unit?

Thanks for any advice!