Thanks a bunch! I did put the update on the SD card, inserted it, connected battery and it immediately started updating. This is actually a device I want to repair so this is certainly a step in the right direction.
I am now able to set it up using Wi-Fi so it is usable, except the USB Data issue still persists unfortunately.
I did resolder and check the Micro-USB port and it is all fine. Even checked the data- and data+ connections from the lead all the way through the smd components to a via on the motherboard which goes straight to the Freescale processor.
I'm currently at a loss as to why USB connection is not working. Tonight I'm going to check the traces and the via's (they're on the "display" side of the motherboard) again.
If those are allright I suspect one of the two support components which the D- and D+ signals go through. If those are not hindering the signal it probably is a broken connection on the BGA and will need reflowing of some sort.
If anyone has any information of the components residing on the USB Data lines and how I should test these please let me know. They look like a tiny transistor and a dual mode coil (Board says LC) so probably a coil. Attached a picture so take a look if you're interested
https://imgur.com/pETzISD