@manyeetit well,you do have to open it. Use a good screwdriver when trying to open it. Always use a new driver since an old one can "chew up" the screw heads. If that happens, you can usually drill them out. Just use a drill bit about 3/4 the diameter of the screwhead and drill slightly through the center of the screw. That will most likely break off the screw head. If it does not do that, use a slightly larger drill bit.
Once you split the case, you can remove the rest of the screws with a pair of pliers. Now comes the fun part. Time to disassemble your device and to clean everything with +90% isopropyl alcohol and a soft brush. For a proper cleaning, use this guide. It was written for an Apple iPhone 3G but it is still pertinent to your PSP as well. I can not stress the importance of a good cleaning enough, so do it over and over while replacing the alcohol after each cleaning. Do not use compressed air for the cleaning since that can drive liquid, as well as corrosion particles, into areas that will cause trouble later on.
Once cleaned check for corrosion damaged like lifted traces, corroded via's as well as failed components. Post some good pictures of both sides of the circuit board with your question. That way we can see what you see and hopefully guide you further. Now, if everything looks good and you are sure about not shaving any corrosion issues (check the fuses as well) get a new battery and see what happens :-)
PSP E1000
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