Black Lines + Annoying Ringing?

Okay, so my PSP has recently started to randomly generate a strange and incredibly annoying ringing noise, which continues to sound even when the sound is muted. At the same time, the screen is covered with black lines that seem to vibrate, which end up eliminating nearly all visibility. It doesn't just occur in gameplay, it occurs in the xmb menu too. It used to only happen rarely, but recently when my dog knocked it off my kitchen table, it began to happen very frequently, and the only way you can make it stop is shaking it up and down/ back and forth rapidly or smaking it. As you might have guessed, this SUCKS, especially when you're playing RE2 or RE3. I think a part may be damaged, but does anyone know if it is something else? Or, failing that, what part I would need to replace and how? I can't afford to buy a new (or used) PSP anytime soon, and my warranty has not only long expired but has also been voided by installing M33 firmaware, so I don't know if Sony can/will repair it.

Also, it is a fat PSP with 3.90 M33-3 firmware. And don't tell me to just get a job, because 1.) I'm not of legal agefor a job and 2.) The jobs I am elligible are ones that my parents will not allow me to have. I don't get an allowance either. Please help me with this issue.

Thank you in advance for any help or suggestions offered.

Hi,
About your warranty, you could try installing official firmware so it appears normal and sending to sony (remember to remove your mem stick) and see what happens. I don't know if this means they can't see you've had custom firmware but it seems it may be your only option. I wouldn't try this until someone else verifies that i'm right though,

Angus

Thanks for the suggestion at least....