I think I broke my gameboy..

Hi everyone , the other day i was changing some parts of my gameboy, modding the cases.. and accidentaly i placed the battery the other way around to turn it on while it was disarmed, obviously it didnt turn on and i realized i put the wrong way, but when i placed the battery the right time this time it didnt turn on either, did i just fry the motherboard or something becus i tried to turn it on with the battery placed wrong?? if so what did i break and how can i fix this!? ive had this gameboy for more than 10 years now, and i dont want to lose it :c help