Arduino LCD problem on VEMS V.3

[Audis6]

my V.3 VEMS motronic55 been running great for years.recently i had a problem with my LCD.firstly
i guess my LCD was the culprit so i ordered the 20x4 Arduino replacement.at first attempt it seems
the LCD is working flawlessly then only backlight left on the display.sometime it's blanking on
2lines as you seen on my photos uploaded..I'm wondering if there's something wrong with my genboard.any procedures to check on this thing?

[Audis6]