To get rid of the NV4 error open services.msc & disable the Nvidia display driver "helper" service. This is a know issue with Nvidia drivers & it's removal will take care of that issues & causes no side effects.
(it's a debugging service)
Most likey your problem was rellated to AS5 contamination or not having the LCD ribbon inserted fully as I stated earlier.
I'm glad your issue seems to be resolved!