My iPod won’t turn on

Hello everyone,

A while ago bought 3 iPods online with some minor problems, but all of them booted up. I started to disassemble them and swapping the parts in one of the 3 iPods and it worked. up until now it worked like a charm but for some reason it won’t boot up anymore, i tried to swap batteries, i tried it with other hard drives, but none of it worked, i used another logic bord to test the components and there was no problem to be found. Im all out of idea’s so is there anyone that knows how to solve my problem?