With the newer,non-sd card devices,its a bit differently to flash files via hboot. It can be done,with a correct USB OTG adapter,but placing a PxxxIMG(PNG07IMG for the one) onto internal does not work. The common method is to use fastboot and RUU mode wich may seem complex at first,but is actually pretty quick and easy once you do.it a couple times.
This is actually has been my favorite means of installing those files with all phones(even the inspire
) as It does not reply on proper name or sd.format,and the command.window gives you more info when a file fails to flash. Plus,I find it tedious to have to transfer files on and off of the sd card. I used it to install your firmware file on my inspire
I agree 100% with hadron. Once you've got s off,there is never a good reason to go back! Just keep in mind the responsibility of having a device that does no security checks,as it will happily let you brick it
just make sure to know what you're flashing,don't flash things unnecessarily,and make sure to double check the integrity of anything you flash by verifying its md5 sum.