Hello, Bohan… Thanks for your quick reply…
No, unfortunately it's not just the display: as this happens, the sound becomes progressively degraded and disappears in the end…
OK. You may try
1. Reinstalling its firmware by using the Direct Updater, which is bundled within H9 Control. It can be found if you click "Window" -> "Open Eventide Direct Updater" in H9 Control's menu bar on Mac, or by searching "Direct Updater" on Windows's start menu. You'll need to boot UPDATE mode by powering up the unit with HOTKNOB button pressed and held to do the update.
2. After update, try a factory reset by powering up the unit with the right footswitch and the black encoder knob pressed.
If these don't fix the issue, you should email email@example.com and consider to send it in for repair.