This is one of the reasons we do not endorse the use of homebrew on the system- some of it can be a bit questionable in coding quality or even in honesty about what it is supposed to be.
You could try taking the memory stick out and turn on the PSP- maybe not having the program file in there will let you start up properly. I would advise removing that from your memory stick as soon as possible on the PC.
If that doesn't work your PSP is toast and you will have no choice but to get another one. You could try contacting Sony if you are still under the one year warranty for a replacement, just don't mention how things got the way they did.