First of all, there are three parts here...the backlight bulb, the inverter board, and the wires going to/from the inverter board.

The bulb typically fails by tinting orange, then going out, but sometimes, just like a shop light, the bulb starts flickering.

the inverter board tends to work or burn up

The weak link is the cable, and where it plugs in.

some laptops have the inverter in the main chassis, and run the high-voltage to the display through a shielded round cable or ribbon, either of which are fragile.

Some have the inverter board inside the display, and they run low voltage cable from main chassis to power it up.

In your case, I would guess either your inverter lamp is on the way out,one of the cables is damaged, or one of the cables is partly unseated (due to the fall).