Chosen Solution
Replaced complete LCD digitiser front case initially trouble with display lighting up however soft restart solved this, at this point damage was spotted to cable for home button this was ordered in the meantime while awaiting for cable phone worked as normal The issue started when plugging this cable in, initially plugged in wrongly but spotted quickly and reversed plug screen was lite to begin with but slowly darkened and eventually nothing form phone wont start up no response from Itunes tried most things on this site At no time has LCD plug cover been refitted so dont see that there could be damage at that end. Thinking a voltage missing but have no schematic to follow.
This is a belated answer so hopefully it can be of use to folks who search for and find this question. Whenever a flex or connector is put in improperly, you always run a high risk of shorting out important voltage rails. This in turn can cause damage to the entire subsystem and in some cases cause boot failures. Unfortunately, this kind of failure is not really in the realm of DIY repair unless you understand how to read a schematic and have the proper tools to probe and eventually repair the logic board. For the OP, at the time of the question, schematics were probably not even available. As for repair, look locally for a reputable shop that does micro-soldering repairs. Ideally, you want to find someone local but good workmanship trumps locality. There are many shops worldwide that do this so you shouldn’t have any problems finding them.
