Sovol SV06 blank screen

Hello, I bought Sovol SV06 in mid-July, I faced a problem two days ago that the display is not working while the whole printer is working fine. I checked it with a USB cable and it worked when I connected the printer to my laptop or to a power bank and it could work and print, however, when I disconnected it, it didn’t work again. I tried to put the last Firmware again but the printer already has the previous Firmware. So please tell me what should be done exactly?

I had this happen once, restarting the printer did not fit it…but shutting it off & restarting it 30 min later did.
I don’t know what it was or what caused it, but I haven’t seen it since.