iopd wont turn on at all

firstly my ipod did suffer from water damage but i quickly let it dried out and then fully chaged the battery, then i noticed that the ipod was now unable to turn off so the battery was continuously leaking power. then my girlfriend unplugged it the other day and the ipod wont turn on at all. i have brought a new battery and have fitted it in but while i was fitting it in i accidently broke the cable next to the hold button. since that ribbion has snapped now the ipod wont turn on. just wondering but would i have to replace that ribbon to get the ipod working or will i have to replace the motherboard?

and the last question is can i use the current hard drive in my ipod as a external drive? if so how can i cause i have some college work on it

thanks for the help.