My LCD screen shows only 2 lines of blocks!

[wenganxiang]

I am using Geeetech Prusa I3B, with LCD 2004 smart controller, and the printer has been working perfectly for almost a half of year. Yesterday, when I was printing, the LCD suddenly showed only 2 lines of blocks!
At first, I thought it was just constrast issue, but after I adjusted it, the screen still not worked, I checked the connection of LCD for many times, and I can confirm the connection is fine. I can not find any other solution. Can somebody help me? Thank you in advace.
LCD.jpg

[printbus]

The 20x4 displays show those two rows of blocks until properly initialized by whatever is driving it. This could be either the hardware not wired properly or the firmware on your electronics not being configured for the proper display panel.

[wenganxiang]

The 20x4 displays show those two rows of blocks until properly initialized by whatever is driving it. This could be either the hardware not wired properly or the firmware on your electronics not being configured for the proper display panel.

After re-uploading the firmware for some times, it works again now!. I think maybe its is communication issue that cause the firmware was not completely upload to mainboard.