what is modchip? :)

You should ask him what Hex Code download he used. If it's NEO2.2, then if he did it properly, you've got something useful. The easiest boot method is DVD Region X. You boot the PS2 with DVDRX, when the numbers appear on the screen, press EJECT on the PS2. Swap in your backup game (preferably made with CloneCD) and press START on your controller. It should boot. The AR2 method isn't a lot more complicated. So now you need to

a) Ask the above question
b) try it out