Gigi Biru you have a lot going on here. “it keeps restarting again and no more choice for advance repair again, I’m stuck at boot loop. And I can’t enter to BIOS due it automatically disable. “if you cannot access the BIOS you cannot change the boot order to boot from either a CD or USB port. This will make it difficult to replace your OS. It is also hard to make out if your display issue is a settings issue (which may be set out of parameter for your internal and external display). For now I would stop assembling and disassembling your computer. Try to reset the BIOS. On the Acer Aspire V5 series, open the bottom cover and remove the RAM. There should be a couple of pads on the board labelled G2201. Remove the battery and power cord as well. Use a paperclip or a piece of wire to short those two pads. While holding the wire, plug the computer back in, then push the power button. This should clear our BIOS. For as long as your cannot access your BIOS you cannot get a new OS. Let us know what you get. Don’t do many things at once because it gets confusing and it’ll be hard for you to figure out where the problem really is. After all with the history of this computer it could be the LCD or it could be the hard drive etc.