Hi!
A lot is tried already! At this point it would be a great test to see if it works with AV and HDMI. So, if you have connected it to HDMI now, please try AV and see if you will get a screen there. If not, then it is something on the motherboard (there is a known IC that can fail and if this happens, you won't get any image, I forgot the name of the IC, sorry).
Also inspect both ports from the outside to see if they are OK or not.