PSP-3000, temporary/manual PRO-C 6.60 CFW.
Tried to start an official PsOne Classic: shut down, not turning on, not charging (no LED). Did not have that much battery in it at that time but I don't know if that has anything to do with it.
Now to be clear, I have tried this with another official PsOne (.eboot) file on cfw but it had worked perfectly.