So no fan spin i am assuming? I would try taking of connectors (keyboard, trackpad ect) and plugging in one by one to see if one of them is causing an issue. See if you can get fanspin with no keyboard / battery plugged in
Are you trying to boot into recovery mode in order to install an OS? Perhaps try putting it in Target disk mode (Hold down T when starting), and install OS via thunderbolt cable from another machine, and see if you can the use external display
It likely isnt a faulty speaker if it works when ringning. I would suspect a software issue. Take a full backup, and then restore the device. Try setting up as a new iPhone first, and then restoring with the customers data
As the others have stated, you need a P5 Pentalope :-) Be aware that the harddrive is not a standard 2.5 SSD, but rather a flash-drive where you also need a special tool to read and transfer data
Have you tried replacing the longflex, running along the screen? Have seen other cases where repeated removal / several screen replacement causes this.
Ports are on the logic board, which is mounted in the top case. Top case is mainly battery, keyboard and some other small components. It should be under warranty if your model is this new
Please note that the part for this EMC number os 604, and not 601