i just did this to a verizon galaxy S and had to do vol up+vol down+ power and then release power button only when logo comes up, then I had to use the touch screen buttons at the bottom, the one with an arrow pointing upward, to confirm my selection to factory reset. Slightly confusing but it worked.
For the Ipad 3 the flex is LONG on the lcd as well as tough to get flush into the socket. Make sure that is flush into the socket as well as check in the connector itself for debris. Make sure that long flex is not twisted or bend getting into the left slot.
take a screw driver and put super glue on the end and let it rest on the top of the plug, leave for a while and hold firmly. Once dry slowly remove. Had to do this for an iPhone in my shop earlier this week. BE PATIENT !!!!! and careful.
There are 2 screws on the top of the board which are for grounding for the proximity sensor I would say comfortably that one of them is for that purpose. Check the top of the logic board, there is a set of screws where one screw goes into another on the top and the lower one hold in a metal clip, that one is commonly missed. Also by the camera assembly there is another screw that is forgotten because of the shield being able to hold all of those goodies in place it tends to get overlooked. It is underneath the shield top left corner should be 2 screw holes close together, may also be where you forgot them.
There are 2 things that can cause this usually. 1st the Power supply has died. 2nd the power cables have become decoupled from the Motherboard due to electric blow back. Re seat all of the power connection within the computer and retry powering it on. If this does not solve the issue try a new power supply. Make sure you purchase the correct PSU for your system. Verify by the model number. Guide for PSU replacement : Power Mac G5 Power Supply Replacement
I would recommend a new battery. Guide here: iPhone 4S Battery Replacement Part Here: iPhone 4S Replacement Battery Tools here: Phillips #00 Screwdriver P2 Pentalobe Screwdriver iPhone *PS DO NOT USE a cheap Ebay screwdriver those screws strip VERY easily and are near impossible to remove otherwise.
First the Samsung Galaxy 2 series has MANY sub models make sure that the parts you ordered are for your SPECIFIC model, I know this is stupid however there are SOOOO many models of that phone. Second off may want to try a hard reset on the phone if possible. Third make sure the screws are all in snugly, for most modern smart phones the screws also do a fair bit of grounding and if one isn't seated properly it make cause weird issues. Lastly take an eraser and press it firmly but gently onto the screen and see if you can get the colors to change, if they do not shift into a rainbow or jet away from the eraser I would say the LCD you received is faulty.