Needing to access the information on my phone with unresponsive touch screen/digitizer I have done some thinking and experimenting.
To TEMPORARILY restore the functionality: DO NOT use the 'press the power button hard/repeatedly/alternate pressing hard on each side' technique
- this will only damage your power button as well.
The ribbon from the digitizer runs down towards the back of the phone just the above power button. Due to poor design, the power button likely brushes against and causes movement in the digitizer ribbon cable causing fatigue in metal in it resulting in cracks in the wires/copper strips.
Functionality of the touch screen goes on and off as these cracks (more likely just one crack) opens and closes causing the reconnection and disconnection. The best way to cause movement in the ribbon to cause the cracks to temporarily close is to rub your thumb in a circular motion or up and down on the power button to get it to touch the ribbon - you do not need to press hard.(Edit: try rubbing your thumb over the power button it in a circular motionwhile holding it down - still do not need to press hard)
To keep funtionality as long as possible
, avoid pressing the power button and be careful pressing the back button - press it only straight down and gently. Keep it charged and switched on. Wake it up using the talk/send key. Don't put it in your trouser/pants pocket where the button will likely get a lot of side to side movement while walking - in fact, this may be what kills it in the first place. If you do put it in your pocket, put the buttons at the top facing away from your leg or use some kind of case to prevent the buttons receiving pressure/movement. Press touch screen only gently in that lower-left corner. If you need to switch it off, do so by taking the battery out. Switch it on by connecting it to a computer via USB. Be careful when polishing smear off the screen - avoid that power button.
To find out what replacement part you need - replacement is inevitable
(unsure if this info is accurate, but it seems right)
Turn off then turn on while holding vol down to get screen with red/green/blue bars. Look at bottom right number. If it reads 0x30 its solder type (295), if it's 0x50 it's plug in type (300), if it's 0x40 I've no idea, maybe plugin (300 type) - so I read...yet to fix mine. Take battery out to reset back to normal. Most UK/EU are solder type. If it's has T-mobile on the front it's plug-in type - so I read.
---------- Post added at 12:15 PM ---------- Previous post was at 11:54 AM ----------
Lots of positive feedback on HD2 digitizers it seems from this seller - let me know how you get on if you buy one. What is the quality/fit like? I read one seller was supplying plastic ones - not glass (but he/she said they were actually ok) - not sure if this seller supplies the same.