I had read here earlier that this error would be due to the IC1 CD4050, however I got a new one today and put it on the board. The problem is still not resolved; I still only get to see the blacklight. I then reheated all the soldering tips (so that the solder might adhere better) and tested the connections with a continuity measurement. Nothing will help.
I have measured the components according to the schematic and conclude that it is not the CD4050, this IC works fine; However, I do not know if the output voltage of the VR3 (LP2950-33LPE3) should be exactly 3.3V? I measure a voltage of 4.3V. The input voltage is indeed 5V.