Guys, I'm new here and I badly need your help.

Two days ago, I was playing with my PSP slim. Suddenly, command buttons (square, triangle, x and circle) buttons don't work. I tried hard resetting and removing the battery, and still the buttons didn't work on the XMB. I also tried running the PSP on the recovery mode, but there is still no response from the said buttons.

Other buttons are functional (start, select, home, volume, sound, L and R triggers and backlight). What should I do? Is this a software or a hardware problem?

*note: I wasn't able to check my firmware version, since the buttons are not functional.

Thanks in advance.
Have a good day. :)