Hi i have psp , but it doesnt power up ,

Hi i have psp , but it doesnt power up ,
only green diode shines, but sometimes
after many tries it powers up but
it doesnt work properly , you can go trough
menu but cant change theme or something .
Whats wrong with that , could it be fixed
somehow ? i tried for second time to flash
this psp , for the first time i went good , but
now the green diode shines cca 3 seconds and
then doesn shine with pandora battery and
magic MMS . I dont understand it , if you do,
please help me , thanks . Tomas .