1) Check the white thin cable ( flex cable ) on the board if it's kind of loose.
2) Check the brown cable placed at the back of the LCD, see the underneath if it's kind of loose or try to wiggle if loose. Loose connection will give you black screen. Reconnecting it back will fix the issue but you need to carefully remove the PCB board attached at the back of the LCD by an adhesive tape.
3) Next is check the C116 component on the board and try to solder 220pF capacitor on it. This is if you're are comfortable doing so.
4) Last is U4 component, with a magnifying glass check the gold pads on either side of the pins if the soldering is good. Silver means good soldering if it turns gold it's bad one. Re-tinning the pads will resolve the issue.
When issue persist open a support ticket by clicking 'Support" button in our website.