How do u downgrade a psp slim cfw 3.90 m33 to a ofw or cfw?

i converted a phat psp battery to pandora with despertar_cementerio4 and os pandora battery creator from my other cfw phat psp or my slim but when i put the battery and memory stick in the slim and turn it on the green light turns on for a 1 or 2 seconds then turns off can u tell my why