Kobo Clara BW: screen turns grainy / goes black seconds‑tens of seconds after replac

[zchmh]

Hello everyone, I’m an e‑ink e‑reader enthusiast and new member here. I hope to get some advice from experienced users.
I have replaced the screen on my Kobo Clara BW. After the replacement, the display works fine right after a refresh. But within several seconds to more than ten seconds, the screen develops heavy grainy noise (mottled dots).
Hardware connection is double‑checked. I suspect this is caused by mismatched panel parameters, and I believe I need a proper custom waveform / LUT file matching my new screen to fix this VCOM‑related display issue.
The VCOM value has been adjusted. The difference between the system‑configured value and the value for the replacement screen is within 20. According to relevant references, this discrepancy should not cause the screen‑blackening issue. Therefore, the most likely culprit is the waveform file.
Could anyone share guidance on generating or applying the correct waveform file for this replacement panel? If you have related experience or working files, I would really appreciate your help.
I can provide my screen panel model number and other details if needed. Thank you very much in advance.