won't boot to os after replacing dc-in board

I just replaced my dc-in board after receiving a solution in a prior question. see while running ac power adapter turns yellow and stops charging if move

Everything was working fine before and I was very careful to not move anything other than the parts I was replacing-followed the great ifix it tutorial to the letter. Now the green light stays on- the part where the adapter goes in had the plastic inner casing worn down so the adapter wouldn't stay in thus my previous problem with the green light staying yellow & not charging. Now when I turn on computer the OS won't boot up (I think). It sounds just like before booting up but all I see is a grey screen with a question mark flashing interchangeably with the Finder icon inside a file icon.

Please help

I purchased the recommended tools and a new dc-in board. Did I inadvertently damage something or could it be something else?

Thanks