I am trying to upgrade to 3.71 M33. My current firmware is 3.40 - A OE. Whenever I try to upgrade to 3.52 M33 my psp says that 150.PBP can't be opened. After I had tried this for awhile, I decided I would downgrade to 1.50 and then upgrade up. Again, my psp says that the UPDATE.PBP (1.50 fw) cannot be found. I had one last idea of trying to re-flash my psp on 3.40 and maybe that would help. Again, the psp said that 150.PBP could not be opened.

I have gone over and followed the instructions completely. Everything is in its right place, and named correctly.
Nothing related to 1.50 is working.

I have downloaded numerous different 1.50 updates, and none of them have worked btw.
Can somebody help?