Question about what I should do about my modded PSP

I bought a PSP in 2007 which I modded. Now, nine years later, I am beginning to have some problems with it. The start button keeps reacting as if I were pressing it without me pressing it, and the volume turns down without me pressing it as well.

I was wondering...what is wrong with my PSP, and should I get the PSP fixed, if it were worth fixing, or should I purchase a new modded PSP off ebay, or buy a new PSP, and mod it myself?

What would all of you recommend that I do?