Do those images mean that the hboot would not run the PB99IMG.zip? If you have not tried that, try it first.
If it will not work, then you need to install "fastboot" on your computer. If you use Windows, there are some instructions here: [FAQ] ADB and FASTBOOT for Windows (Updated 1st June 2011)
Then download the bravo_stock hboot image: bravo_alphaspl.img
Then connect your phone to the computer using usb, and use the command "fastboot flash hboot bravo_alphaspl.img" to install the hboot image.
Once that is done, reboot the phone. Then download the RUU you want to use as a Windows .exe file (not a PB99IMG.zip), connect the phone to a PC via usb and run the RUU .exe. That should fix it. Which RUU do you need (what network, for example)?
Given that we're communicating via google translate, it really would be best if your friend who originally modified this phone could help you.