Chosen Solution

So I’ve been buying and fixing 3DS hanhelds off of ebay for a few monthes now and it’s been going pretty well, until one of the three handhelds I bought started giving me trouble. with everything put back together it will not power on, at first I thought it was a dead mobo but after buying a new one through ifixit it still won’t power on( there is a very brief blue light but it goes away almost instantly) I have tried the same motherboard in my test handheld and it works perfectly. I have also swapped the battery with no luck. I’m wondering if a faulty home button or something like that would be enough that the console wouldn’t be able to power on. from what I can tell there’s no damage to the display ribbon cables either if anybody can help me I’d greatly appreciate it.

Does it turn around 5 seconds with blue light and then turns off or it just doesn’t turn on ?