Did you format the USB drive first? Eazyflash doesn't work properly if there are folders and such on the drive.
if you are out of warranty the only cheap fix is reprogramming the bios with a spi compatible programmer you will need to check your motherboard uses an spi flash chip I assume it does, i reccommend the buspirate, this is very easy to do as well esp if you have a soic8 chip clip. You should only need to spend $40-50.
You will need to research the chip pinouts and match with the buspirate pinouts, best way is to get a soic8 clip and an adaptor board, and attach the clip, a small indent on the chip usually denotes pin 1.
And you will also need to get the latest flashrom which has buspirate support, install drivers for buspirate and note what com port it uses and replace 'COM3' in the console commands below with your own.
1) assemble the clip and buspirate according to pinouts etc and attach to the bios chip.
-in Command Prompt do 'flashrom -p buspirate_spi:dev=COM3,spispeed=1M' it should detect your bios chip and display the name of the chip. If it does you are in business.
2) You wiill need to read your bios flash chip contents with the latest flashrom and save as 'g53-bricked.bin' the filename isnt important but just so you know what is what.
-Do 'flashrom -r g53-bricked.bin -p buspirate_spi:dev=COM3,spispeed=1M'
and verify 'flashrom -v g53-bricked.bin -p buspirate_spi:dev=COM3,spispeed=1M'
3) Download the latest bios update from the asus website. Extract and save as 'g53-update.bin'
In a hex editor you will need to overwrite the contents at the end of 'g53-bricked.bin' with the contents of 'g53-update.bin' so the file will resemble what it should have been had the update been successful in the first place. Save as 'g53-unbricked.bin'.
4) using flashrom write flash chip with 'g53-unbricked.bin'
-Do 'flashrom -w g53-unbricked.bin -p buspirate_spi:dev=COM3,spispeed=1M'
5) Laptop will work again.
This is the buspirate setup when I unbricked my own G74SX.