If you have an Asus F5R laptop that will turn the power light on and maybe other lights, but won’t POST or Boot, and may refuse to turn off as well when you hold down the power button; it might just be the BIOS battery.
I had one come in with the same problem – has been sitting for a year or so by the looks of it. Internal battery was at 0.4 volts instead of the required 3 Volts.
Replacing the battery means removing every external screw including the two at the back, removing the keyboard, unplugging pretty much everything internally and finally lifting out the mainboard. On the back of the mainboard near the external monitor connector is a CR2032 battery. Replace it and your laptop might come to life. You can safely power it up for a short time with just the board and an external monitor to see if you get the BIOS screen before bothering to reassemble it. (A USB keyboard won’t work in this instance.)