In this case, the actual laptop is Dell Latitude D630.
First of all, please shut down your Dell Latitude D620 / D630. Disconnect the power adapter and remove the battery.
1. Unscrew the (2) 2.5mm x 5mm bottom hinge screws.
2. Unscrew the (2) 2.5mm x 5mm hinge screws on the back edge of the laptop.
3. Turn the laptop over and open the display. Remove the Hinges Cover and Keyboard. You can find the instruction here How to Replace Dell Latitude D620 D630 Keyobard.
4. Disconnect the WWAN antenna cables and the WLAN antenna cables. Unpug the LCD Cable (In other words, disconnect all the cables from LCD display assembly to motherboard). Remove these cables from their routing channels.
5. Lift the LCD display assembly away from the laptop base.
6. Remove the six screw hole covers. Unscrew the six 2.5mm x 5mm x 1.5mm bezel screws.
7. Starting at the bottom of the LCD screen, lift the bezel until it unsnaps and work your way around the edge of the screen.
8. Unscrew the (2) 2mm x 3mm screws at the top of the screen.
9. Unscrew the (6) 2.5mm x 5mm screws at the bottom of the screen.
10. Lift the Dell Latitude D620 / D630 LCD screen from the LCD back assembly and turn it over.
11. Unplug the Dell Latitude D620 / D630 LCD Video cable from the LCD screen and inverter.
12. Unscrew the (8) 2mm x 3mm screws and remove the mounting rails on the left and right sides of the LCD screen.
13. Unscrew the (2) 2.5mm x 5mm screws on the left and right hinge.
14. Remove the hinges. You can find the replacement here: Dell Latitude D620 / D630 hinges.
15. Unplug the Dell Latitude D620 / D630 LCD inverter cable.
16. Remove the Dell Latitude D620 / D630 LCD inverter screw. Slide the LCD inverter out of the mounting bracket. You can find the replacement here new Dell Latitude D620 / 630 Inverter.
Note: If you want to replace the inverter only, you don't need to removing the complete display assembly, you can skip the step 1-5 and 11-14.